A tall man, thin, balding slightly, but on the whole fairly nondescript, took advantage of a temporary lull in pedestrian traffic to cross one of the walkways that spanned the wide gallery deck. Below him people from a hundred worlds bargained, haggled and argued at sufficient volume to make individual conversations impossible to decipher for any besides those directly involved. Merchant captains shoved their way through crowds of opportunistic traders, who in turn tried to sell them anything that could be sold. The scent of strange foods wafted through their air, and brightly coloured signs advertised the hundreds of tiny stalls and shops that crowded both the inner and outer walls of the gallery. The crowds were thinner on the balconies running along both walls, and mainly consisted of organised business, as the narrow walkways and crossover bridges ruled out the possibility of any sort of space from which to sell anything. A pair of station guards, Navy soldiers but outfitted in the carapace armour common to the security forces of such places, pushed through the crowd below as the unremarkable man left the bridge and waited a moment until the movement of people gave him a chance to approach one of the tall steelglass viewports. He stood for a moment, staring out with the lights of the gallery shining past him.

From outside his was just one of hundreds of identical points of light shining through the dark metal hull of the gallery. Below were row upon row of docking ports, almost a mile of them in total, most occupied with ships of one sort or another, from sleek diplomatic transports to scarred trader shuttles, the golden hulls of Adeptus corvettes next to the grimy shapes of bulk freighter pilot modules, their huge cargo bays orbiting a safe distance away. Further still, below the docking ports, the massive bulk of the fusion reactor core surrounded the thin, needle-like communications array which jutted out into space, clear of the interfering presence of engines and electrical systems. An automated service elevator, containing the misshapen forms of a pair of vacuum-adapted servitors, was just beginning the long journey from the antenna maintenance module at the very bottom of the array, up towards the cargo decks which towered above the gallery and docking ports like the skyscrapers of a planetside city. Above these vast storage bays rose a giant eagle, its metal wings stretched out towards the stars on either side, its eyes glowing, staring out into space. Within, the tiny figures of the station's bridge crew could be seen moving about, attending to the needs of the massive structure beneath them. Their was the responsibility of ensuring that the dozens of ships arriving and departing during each simulated day were properly docked, their cargo stored and transferred, their flight paths in and out of the docking zones calculated and monitored, their crews accommodated within the gallery module's thousands of transient quarters. It was an endless task; the sector was a crossroads of a hundred different shipping lanes, and the only Imperial facility available was Ascension Station.

The man looking out of his porthole directed his gaze downward, beyond the carefully-planned movement of the incoming and outgoing ships, to where the edge of a red whirlpool was just visible. This had been the reason for the first sections of the station to be built: the Volcano Gate. It lived up to its name, for the warp gate appeared from above to be a mile-wide circle of molten fire, churning as if continually stirred by currents under its surface. It was only later, when the need for a merchant spacedock was becoming more apparent with every passing year, that the tiny monitoring station that watched the Gate for signs of life beyond began its transformation into the spaceborne city that it now resembled. Before then, the Imperium had barely been convinced of the need to watch Volcano Gate at all, for unlike the other warp gates scattered around the galaxy, those that were somehow able to stabilise the warp from one point to another, this one was nothing but a permanent opening into the warp, a redundant resource for any ship with a warp drive. Aside from avoiding direct contact with the Gate and its underlying currents, either here or in the warp, the captains of the ships passing through Ascension barely gave it a thought. After watching the rippling patterns of reds and yellows for a moment, the man at the porthole looked back up, into the dark depths of space.

His eye fell upon a lone ship floating towards the docking ports, and his eyes narrowed. The ship was low and wide, its engines larger for its size than those of most of the ships already docked, and it carried a selection of weapons arrays that would have outlawed a merchant vessel in an instant. On the communications tower stretching out above the ship's reactor core, the symbol of the Inquisition was already visible to the watcher. Tiny lights flashed on the forward hull, slowing the frigate's approach as it neared the station. All other ships were being directed away, so that the new arrival barely had to change its heading to bring its primary airlocks alongside the docking port it had been assigned. With a final flare of the braking thrusters the ship lay still.

"Well then," said the man to himself, his hand brushing the grip of the neural shredder under his coat, "the game begins."

The whirring of motors added itself to the constant hum of other machinery as Admiral Sator turned to face his visitor. The old man sat at the centre of an assembly of monitors, holograms and controls, the whole of which was suspended from the ceiling of the station bridge by a mass of cables and supports. Several screens retracted to either side of him, allowing him to lean forward from his mechanical cocoon and address the Inquisitor who waited for him, flanked by a pair of adepts.

"This is about the transmission, is it not my Lord?" he asked bluntly. The Inquisitor nodded, and reached an armoured hand to one side. One of the adepts provided a data tablet, which was raised to the expressionless hood that covered the face of the visitor.

"The merchant vessel Star Hammer monitored an unauthorised communication in the region of the Volcano Gate two weeks ago. You failed to report this to the Inquisition, or your superiors in the Imperial Navy. Why?"

"If you will forgive me for saying so, Lord, it is nothing that need concern Terra. The ship was conducting a test of modifications to its warp drive. The signal was intercepted while the drive's interspace field was active, it was nothing more than a normal transmission pulled in by the influence of the drive. Such things have been known to happen, and my technical crew confirmed that the signal was most likely an Imperial one that had been distorted beyond recognition. I saw no threat, and therefore no need to include the incident in my reports."

Inside her hood, Vail raised an eyebrow. She had already reviewed the details of the assignment she had been given, and had found that the Admiral's version of events was the most likely answer. Nevertheless, she found it always paid to be thorough.

"It is not up to you to decide what Terra need be concerned about. Clearly there is a need for further information regarding this signal, or I would not be here. Your reluctance to include this in your reports merely adds a complication." Admiral Sator leaned back in his chair, slightly uncomfortable with the direction the interview was taking. His eyes darted across the various displays that were now back in his field of vision.

"You will provide my adepts with access to the station's technical resources. Whatever they require. You will also provide my ship with complete data transcripts from the five hours surrounding the detection of this signal, both from your own equipment and that of the freighter. You do have the transcripts from the freighter?" Sator nodded, making notes in a data tablet as he listened. "Very well," Vail finished, "remain available. I may require further information from you, if that is the case you will be notified. Good day Admiral." Vail turned and left the bridge, her adepts trailing in her wake. Sator watched the trio leave, then turned his attention back to his station.

"Let's run this through again," said Vail as she paced restlessly around her rooms on board the frigate Nova. "We have a signal. This is intercepted during a test of the freighter's warp drive. At the time, the drive's interspace field was active, so the ship in realspace could have accidentally intercepted a transmission that was actually in the warp. Correct?"

"Confirmed," answered the microcomputer she was flipping idly from hand to hand.

"And the interference from the interspace field distorted the signal, so that it's impossible to tell whether it was Imperial or not."

"Confirmed."

"And the station communications array was active at the time of the signal's interception, but recorded nothing because the signal wasn't sent to the station, and it wasn't affected by the interspace field."

"Imprecise wording," said the computer, "Ascension station did not detect the signal because it did not broadcast an interspace field of its own. Freighter's interspace field did affect station communications array, requiring harmonic adjustment to allow communications to continue to function normally."

"Yes, that's what I meant," said Vail, returning to stand in front of a hologram floating above her desk, showing streams of data representing the station's data communications transcripts. She was about to turn away when something caught her eye.

"Wait," she said quietly, "freeze this section." The hologram flickered and was still. "This is the station data during the drive activation, yes?"

"Confirmed."

"Then why," said Vail, running a finger along the glowing curve representing the carrier signal, "doesn't it show the interference from the freighter? The harmonic adjustment should be visible, shouldn't it?"

"Confirmed, no harmonic adjustment is recorded."

"But you just said that there had to be adjustment, otherwise the carrier signal would have been disrupted. And it wasn't disrupted, was it?"

"Negative. Data transcripts do not correlate with known facts."

"And if the facts are known, then the data is in error. Scan the transcripts, look for signs of alteration."

"Estimate two hours to completion of function."

"The original data should still be in the communications array core, correct? Procedure requires the core to maintain a month's worth of records. Can you get a data link to the core?"

"Negative. Core has no data links to station systems."

"Alright, I'll go and get the data myself."

After a long, monotonous trip the service elevator shuddered to a stop five miles below the bridge of Ascension. After allowing the two servitors with whom she had shared the trip to leave the elevator, Vail headed out into the cramped maintenance module. Behind the rows of status monitors and databank links she could see the casing of the antenna itself, a wide column that ran through the centre of the module. She inspected the various data connections for a moment, as behind her the hiss of an airlock's inner door signalled the departure of the servitors, on their way to make repairs to something on the outside of the module. Vail found the link she was looking for and connected a data tablet to it, using Inquisition codes to override the machine's Mechanicus security routines.

"Got you," she whispered to herself as unfiltered data began to scroll rapidly across the tablet's tiny screen. After a moment she managed to make sense of the jumble of images. Half of it was the uncoordinated transmissions being sent and received by the docked ships, using the station's antenna to boost their range. More easily recognised were the regular data updates sent by the bridge to sector command, each one the same length, occurring at the same time each day. There was something else, though, another signal. Beneath the clutter of merchant and official messages, there was a single constant waveform being broadcast. It was not dissimilar to the signals used by navigation beacons, showing nothing more than the position of the transmitter, but what would be the point of using such a signal in realspace? It was low-powered, obviously not intended to go far. Vail ran through a mental checklist of possible destinations for the transmission. A ship nearby would have been seen. Something with a cloaking field? No, not this close to a warp gate, the field would break down. The warp gate... Something was moving behind her.

It was nothing more than an instinct, but Vail trusted her feelings when they told her something was amiss. She spun around, dropping to a crouch and drawing her bolt pistol at the same time, grateful for her armour's internal life support should she have to use the weapon here. There was a blur of movement, and she found herself staring at the crystalline tip of a neural shredder, held by a black-clad assassin who was, in turn, looking down the barrel of her pistol.

For a long moment the two stood motionless among the clutter of communications equipment, mirror images of each other. Vail spoke finally, keeping her voice level, forcing herself to remain otherwise still.

"I'm not your target," she said. There was a hint of movement from behind the assassin's mask, but nothing more.

"What makes you think that?" she eventually said. It was not a voice that Vail recognised, but she knew that the Callidus could change virtually any aspect of themselves, voices included. It was, after all, just a matter of changing shape.

"You'll never get a better chance to kill me than now, and you haven't fired." The assassin nodded slowly.

"You're right. But how do I know that I haven't become your target?"

Guessing that there were few situations more dangerous than their current one, Vail slowly lowered her bolt pistol. Once it was pointed downwards, the assassin's fingers uncurled from the handle of her shredder and the weapon's articulated power feed flipped it over her shoulder to rest on her back. Vail returned the pistol to its place on the leg of her armour, while the assassin pulled her mask off and folded it into her belt. That was another trait of the Callidus, Vail remembered: they generally found masks to be redundant.

"I wasn't aware of an assassin being sent here," Vail said after a moment. The assassin shrugged.

"As an Inquisitor," she said, "I'm sure you know Terra better than I do. When have they ever given information for its own sake?" An evasive answer, but Vail let it pass without comment. She returned to her study of the communications records.

"So," she said, "who are you here for?"

"Information," said the assassin, kneeling beside her and looking at the data tablet. "There are ships in the warp converging here. Terra wants to know why, so they sent me."

"Curious they should do so without consulting the Inquisition."

"The Temple takes a dim view of its operatives questioning their orders." Again, Vail noted, she had artfully avoided the unspoken question. An assassin sent to retrieve information? Her mind started to run through possibilities, modifying or discarding them in light of the facts she had so far uncovered.

"So we have the same purpose," she said in the meantime as the assassin left her side to inspect some of the other displays. "We can assume that these ships are connected to the signal that Star Hammer intercepted." The trail of thought she had been following a moment ago reasserted itself. "They're following a beacon being broadcast by this station."

"Probably true," said the assassin. She had retrieved a small device from one of the pouches on her belt and was frowning at it. "I think we're being scanned," she added after a moment. Vail got up and looked at the device, but she wasn't familiar with its type. A data reader of some sort.

"One of the conduits running into the main data connection is carrying a low-level signal. It's waveform is changing in time with our voices. Audio scanner," she explained. Vail nodded.

"That means that whoever is responsible for all this probably knows we're here," concluded Vail. "You stay here, I'll go back to my ship." She raised a finger to her hooded face, indicating silence, then gestured for the assassin to follow her to the elevator. The blast doors rumbled closed a moment later, and the capsule began its journey up towards the station. The assassin consulted her scanner, and found no evidence of further surveillance.

"Now watch," said Vail, pointing down through one of the tiny portholes towards the slowly shrinking module they had left. Vail began to count down in her head. Seven seconds later she saw a hint of movement from the module's airlock, and a brief glitter of dust particles spilling out into the vacuum.

"That answers one question," said the assassin with a grim smile, "our watcher is not friendly. But that only killed me, they still have to deal with you." Vail stepped back from the porthole, beginning to consider ways to avoid the attack which, it seemed, would occur at some point in the near future. Her speculation was cut short by a crash from below. The elevator shuddered but kept rising.

"You were saying," she said, quickly looking out of another porthole. The needle-like structure which the elevator was climbing had been shattered several metres below them, and now only a handful of twisted metal beams held the maintenance module to the rest of the station. She caught a glimmer of reflected light, and then made out the shape of their attacker, circling around for another shot. The assassin saw her attention riveted on the tiny shape, and followed her gaze.

"Remote repair drone," she said, "I've seen them before. It must be someone on the bridge controlling it."

"That narrows down the list of suspects." Vail tried her communicator, then looked up, through the single porthole in the centre of the elevator's roof. "We'll be in the reactor in a moment, I can't get a signal to my ship. How long until it can fire again?"

"Those things aren't armed, so to speak, at least not the ones I've seen. It must be using a cascade shockwave in the plasma cutter to..."

"Spare me the science."

"Not fast. Twenty seconds between shots, at least."

"It's been longer than that already, what's it waiting for?" Her question was answered when the light from the distant stars was blocked by the inner walls of the elevator shaft that drove through the centre of the station's reactor. "Of course," she said to herself, "it can't risk missing us and hitting the power conduits. We'll be vulnerable again between the reactor and the docking section."

"I think," said the assassin, "that it'll get another shot before then." Vail looked to where she was pointing, down the shaft that they were travelling through. The repair drone's spotlights could be seen lighting the walls of the shaft, as it followed them up. For a moment the lights shone directly up towards them, then there was a brilliant flash from somewhere under it's nose and a bolt of energy leapt up towards them.

"Get clear!" yelled Vail, pushing the assassin away from the side of the elevator, where the bolt seemed to be heading, pinning her between the opposite wall and her armour. With a slight pressure on the inside of her gauntlet she sealed the armour and caused its helmet to slide out of its retracted position and snap closed. There was a massive crunch as the bolt struck, then the sound of the impact seemed to fade away unnaturally quickly. Vail turned to see the side of the elevator reduced to a tangled mess of metal and plasteel, its atmospheric integrity lost. She turned back to find the assassin once again covered completely in her black outfit, raising a hand to indicate she was alright. Synskin could protect against a vacuum, of course. Against a plasma blast was another matter.

The assassin moved to the other side of the elevator and activated her phase sword, the ornate gauntlet on her arm suddenly sprouting three feet of glowing blade. She swung a few times, clearing the wreckage away, then waved Vail over to where she had made a hole large enough to see the drone, barely a hundred metres below them. The assassin turned and placed a hand against Vail's helmet.

"Give me some covering fire," she said. Vail wondered for a moment how she could speak in the airless environment, then realised that she was using her palm to generate a soundwave. Such devices were often used to communicate in airless conditions when transmissions were being monitored. Could a Callidus shapeshift accurately enough to copy the idea? Apparently this one could. She nodded and drew her pistol, bracing herself against an exposed structural beam, mindful that the elevator's gravity could give out at any minute. She already felt lighter than she should, one of the gravity mats must have lost a power coupling in the blast.

The assassin opened another of her pouches, then handed Vail the end of a thin cord, pointing to the belt of her armour. Vail looped the cord around the belt twice, then secured it. Without a backward glance the assassin leaned forwards and dropped out of the elevator, giving herself some momentum by pushing against the bottom of the capsule as she left the artificial gravity. Vail aimed carefully and snapped off a couple of shots, both passing more than a metre from the falling shape. One clipped the drone's thruster wing, the other exploded harmlessly on its armour. After all, Vail thought, it was supposed to survive micrometeorites.

The assassin continued to drop straight towards the robot craft, her glowing sword the only illumination. As she neared it the drone's plasma cutter began to build up a charge again - from this distance she could see the tiny flashes of light in its power couplings as it exceeded the safe limits of the device. The searchlights snapped on again, almost blinding her, then the drone itself was rushing up towards her, its rear thrusters casting a glow behind it as it accelerated. She aimed for the plasma cutter, and drew back her sword.

She imagined, illogically, that she could feel the rush of air as the nose of the drone passed less than a foot from her head. She swung her sword, feeling the slight tug as it cut, with near perfect efficiency, through the drone's casing and the machinery inside, spilling raw plasma out behind her. She held the blade steady for a second, then she had passed the drone.

From above, Vail saw the assassin disappear underneath the craft, then a trail of fire erupted from it. It swerved to one side, its stabilisers overcome by the sudden thrust of the leaking plasma, slammed into the wall of the elevator shaft, rebounded across the open space and exploded on contact with the opposite wall. She felt the pressure on the cord attached to her armour increase suddenly, and she returned her pistol to its holster and gripped the cord with both hands, using her armour's enhanced strength to pull it in. Through the cloud of superheated gas boiling away below her, she saw a black shape emerge, curled into a ball, obviously to avoid more exposure than was necessary to the intense heat she had, for a second, been enveloped in. Vail found herself oddly relieved when she saw the shape uncurl and look up.

The assassin had just pulled herself through the jagged hole in the floor when they emerged again into open space, the bulk of the reactor below them. Vail's communicator, which had been automatically trying to transmit since it had been activated, finally crackled into life as the power plant's interference disappeared.

"Nova answering, Lord," said the voice of one of her communications officers.

"Connect me to the internal data channel in my quarters. And," she added before the man could respond, "seal all airlocks and disengage from the station. Prevent any ships from leaving."

"We're still docked, Lord, we haven't had clearance from the bridge to depart..."

"Disregard all orders from the station. Blast the docking clamps if you have to."

"Yes Lord." The channel went quiet for a moment, then returned with a soft hum.

"Princess," said Vail.

"Active," came the answer.

"Access station maintenance logs. A repair drone has just attacked us outside the antenna maintenance module. Find out which bridge workstation was controlling it and report back. Also," she added, glancing at the assassin who, without a contact point, was unable to hear her words, "search the main memory core for all files relating to active Callidus Temple operatives."

"Working."

"Send new orders to the teleportarium. Myself and one other directly to my quarters." The communicator went silent as it was cut from the other end. Vail reached an arm around the assassin's shoulders, and a moment later both disappeared in a column of energy.

The pair reappeared in the centre of Vail's quarters, and Vail immediately called up a display of the station's reactor. The hologram showed a minor breach of a coolant line somewhere inside the power plant, with a small swarm of repair drones attending to it.

"Check maintenance comms traffic," said Vail, "what reason was given for the damage to the reactor?" The assassin, who had unsealed her mask and removed it again, gave a 'who, me' expression in the instant before the computer answered.

"Malfunction in repair drone control system caused loss of control."

"Which department diagnosed the fault in the drone?"

"Bridge."

"Did our attacker cover his tracks," asked the assassin, "or was he the one who reported the 'loss of control?'" She had crossed to the room's oval-shaped viewport, and was looking up at the giant eagle high above them, beyond the rows of docked ships.

"You said that only someone on the bridge could have controlled the drone," said Vail, "are you sure?"

"I'm not sure, but I think so. I wasn't concentrating on the repair systems, but I don't think anywhere else has the equipment to control a drone directly. I know the individual repair bays just assign programs to the drones."

"I doubt there's a 'seek and destroy' program." Vail was interrupted by a tone from the computer.

"Station maintenance logs accessed. Drone control instructions traced to bridge."

"Which workstation?" said both, simultaneously.

"Master control," answered the machine. Vail activated her communicator again.

"Bridge, answer."

"Bridge here," came the reply, clearer than it had been outside the ship.

"Raise teleport shields and stand off to one kilometre from the station. Any station vessels that approach are to be considered hostile. Link the teleportarium to our shields, I'll be visiting the station in a moment."

"The station bridge is teleport shielded, isn't it?" asked the assassin after the bridge officer had repeated his orders. "I had to wait until one of the officers left for some reason before I could get in there." Vail held up one of a small pile of thin discs that were sitting on her desk. "What's that?"

"According to a security scanner it's nothing," said the Inquisitor, "just a piece of metal. But if you send a pulse of delta radiation through it, it resonates and returns a signal just like a teleport homer. I had one of my adepts drop a handful on the bridge when I was talking to the Admiral." Vail bent over her desk and tapped a few keys, activating her ship's transmitter. She then lifted the computer out from under the data tablet that had been resting on top of it, and ut a hand on the assassin's shoulder, ready to teleport.

"Tell me," the assassin said as they waited for the delta radiation to reach the station bridge, "do you always suspect everyone?"

"There may be Inquisitors who don't" Vail admitted, "but I've never met one."

"Sir," said one of the junior officers on the bridge, "there's a delta wave passing through us."

"So?" answered the Admiral from his cocoon of displays, "one of the ships is starting its drive. That's hardly new."

"We don't have any departures scheduled sir," began the officer, but he broke off when Vail appeared directly in front of him.

"Change of schedule," she said. The assassin stepped away from her side, her shredder ready to fire. Vail crossed the short distance between herself and the Admiral and looked at him past the barrel of her bolt pistol. "Consider this a first warning," she went on, "if you tell me everything about the ships that are coming here I'll make sure you merely get assigned to the penal legion. Otherwise I'll have you sent to Terra for a full court-martial. Talk."

"You don't know what you're doing," the Admiral said, "this is more important than you realise."

"Out," said Vail, gesturing with her pistol. The Admiral pulled himself to his feet, allowing Vail to shove him to one side as she sat down. She quickly found the internal communications system and activated it to broadcast over the entire station.

"This is the Inquisition," she said, hearing the echoes of her voice from outside. "In the Emperor's name I am assuming command of Ascension. All crews are to return to their ships immediately. Civilians are ordered to return to their quarters. All station personnel will remain at their posts and take no further action, regardless of other orders they may receive. No ships may leave until given permission to do so." She cut off the system, and turned to the bridge officers who had been herded into a corner by the assassin's shredder. "You're all relieved of duty until a full investigation has taken place. Return to your quarters and stay there. Now, Admiral," she finished as the officers left, "what are there ships?"

"You must let me contact them," he insisted, "if I don't they'll take it as hostility!"

"You've just tried to have us both killed Admiral, I take that as hostility. Who are they?" The Admiral's shoulders slumped as he realised he would get no concessions.

"They are... in their language they are called the Outsiders. They were exiled, long ago, trapped in the warp with no way to navigate or leave. One of my scout ships found them by chance a year ago. I agreed to send a beacon for them, so that they could return to their home."

"And that's it? They told you they'd leave the Imperium alone?"

"They..." the Admiral hesitated.

"Talk, Admiral. I can have a telepath here within two days to dissect your mind, believe me it's easier this way."

"Their home is in Imperial space. They said they'd have to take it back, but if we help them they'll leave us alone. The station, the other worlds in the sector, they don't want any of that..."

"What did they promise you," interrupted Vail, "supreme ruler of your own little empire?" The Admiral's head dropped, and Vail's eyes widened in amazement underneath her hood. "Emperor's glory, how could you be so stupid?"

"They just want to go home," he said in a quiet voice.

"They need a thousand warships to make the trip?" said the assassin, causing the Admiral to spin to face her. He seemed to have forgotten that they weren't alone.

"No, only a handful," he insisted, "they're not hostile, they only want one world. It's their home," he finished, all the energy gone from him.

"Admiral, there are currently five hundred cruiser-sized ships on their way towards the Gate, another two hundred that mass greater than heavy cruisers, at least a hundred dreadnoughts, we couldn't even count how many destroyer equivalents there were. We thought we'd detected a hive fleet at first, does that sound like a force they'd use to take a single planet?"

"The beacon, Admiral," said Vail, drawing his attention back. "Is it still transmitting?"

"Yes, of course," he said, "the damage to the antenna was minor, only the long-range arrays and the controls were hit..."

"Right," she said, cutting him off and activating another communications channel. "Nova, respond."

"Nova here," said her ship's captain.

"Captain, we have a situation here. Hostiles incoming from the Gate, type unknown. Locate and destroy the antenna array broadcasting a signal into Volcano Gate, then maintain defensive position. Your priority will be to protect vessels leaving the station." Vail activated the bridge's main holographic display, watching as the tiny image of her ship fired a lance with pin-point accuracy, severing one of a hundred short-range antennas from the station's main array. She then found a data port and connected her computer to it.

"Access station control functions," she said quietly, "prepare and execute orders for full evacuation using all ships currently docked. Access defence grids and prepare control programs for remote operation. Now, Admiral," she said, again drawing his attention back, this time from the holoscreen which had begun to show lightning-fast displays as the computer began to take control of the station, "you'll be teleported directly to the brig on my ship. Consider yourself lucky. If I'd been these Outsiders of yours, I'd have killed you." Turning back to the communicator built into the chair, she sent a message to her ship. A moment later the Admiral disappeared. Vail then left the command chair and approached the assassin. "These ships your people detected," she asked, "how soon will they be here?"

"Some are already beyond the Gate, but only a few - three cruisers, some smaller types. They're sending their own signals to the others, but without our beacon it'll take longer, we think their transmitters aren't so powerful. It just depends on how long they're willing to wait. The longer they wait the more ships they have, but the more time we have to prepare."

"Then let's prepare," said Vail with a hidden smile. The assassin frowned.

"What do you want me to do?"

"I'm guessing that you're thinking of a way to contact your superiors and call them in. If you are who I think you are." The assassin was suddenly alert, but Vail made no move towards her.

"Who do you think I am?" she asked.

"An assassin without a target. One who can change shape expertly without a direct injection of polymorphine. Only one Callidus could ever do that, according to what I was reading just now," she gestured to the displays that her computer was now connected to. "You're Liela, aren't you? The renegade."

"What if I am?"

"You've got some powerful allies, I hear. I need their help."

"And after all this is over?"

"If we survive, you mean?"

"If we survive, you'll be an Inquisitor standing alongside a rebel force."

"My crew is loyal to the Emperor. Not the Adeptus Terra. If your friends are what they say, there won't be a problem."

"And what about you?" said Liela with a frown. "How do I know I can trust you?" Vail looked at her for a moment, considering, then reached up and removed her hood. Liela's eyes widened for a second.

"Well, well," she said with a faint grin, "the Inquisition's internal security isn't so good after all. But who do you follow, Inquisitor? What do you believe in?" Vail smiled at the question.

"Myself."

"How can it do that?"

Every workstation on the bridge appeared to be operating itself, charting courses for the departing ships, sending and receiving messages from security stations, organising the evacuation of every person from the giant city. Liela was peering at the unassuming book-like metal case that was controlling it all.

"I don't know, exactly. I found it on a frontier world, in the wreck of one of the early Imperial colony ships. Twenty thousand years old, maybe more." Vail returned to the screen she had been watching, which was displaying the bizarrely complex topography of local warp space. She was trying, with the computer's help, to determine how many ships were waiting there, and what they were doing. Interference from the Gate was not helping matters.

"Dark Age, then," said Liela thoughtfully. "I'd have thought the Mechanicus would have something like this locked away on Mars."

"The Mechanicus don't know about her."

"Her?" the assassin repeated with a look of surprise.

"There's some sort of artificial personality buried in there. It's some sort of interface system, without it nothing would work. I've had a couple of people take a look at her - people I trust, some in the Mechanicus - and they didn't even know where to begin with the internal command structures, let alone making the individual relays do anything. It's easiest just to ask her. Wait a moment..." Vail's voice trailed off as she wrestled with the warp sensor controls. "I think something's moving in there. How many ships still to go?"

"Three," answered Liela, "two undocking, one still taking on passengers. Another twelve still getting far enough away from the Gate to jump."

"Damn. There is something there." Vail picked up her communicator, which had been left on, from where it rested on a console. "Nova, we read something coming through the Gate. Be ready to defend the transport ships. Do not," she stressed the last order, "fire until fired upon."

"I thought you'd settled on the worst-case scenario," said Liela as the frigate answered and moved between the station and the Gate.

"I assume the worst. I don't mind being pleasantly surprised though, it just doesn't happen very often. Princess?"

"Active," came the reply, from the station's audio system overhead this time.

"Bring all defence grids online. Lock weapons onto anything that comes out of the Gate, passive sensors only. Don't move the turrets unless they fire on us, Nova or the transports." The holoscreen went blank for a moment, then lit up again with an image of the warp gate below the station. A list of status readouts showed the station's weapons becoming active. "How soon will your friends be here?" asked Vail casually, ignoring the tension they both felt.

"As fast as they can. An hour, maybe less."

"I hope we can hold out for that long."

The Outsiders appeared quickly, three ships simultaneously emerging from Volcano Gate, streams of energy clinging to their hulls as they left the warp. One of the three turned slightly, heading directly towards the station, while the remaining pair aimed themselves at the last of the three ships slowly pulling away from the docking section. Nova executed a shallow turn, coming to rest directly between the freighter and the newcomers.

Each ship was composed of two smooth cylinders, tapering at each end, to engines at the back and some form of sensors at the front. Between these was what seemed to be a weapons module, its surface dotted with torpedo tubes and the barrels of energy weapons. The hulls were a dark orange, seemingly composed of millions of strands of metal laid in a lattice, overlapping so that they covered the entire surface of the ship. There was no sign of manoeuvring thrusters, only the two engine exhausts in the rear of the ships. There seemed to be no markings on the hulls, no distinction between one ship and the next.

Without waiting for warning or communication, the two ships approaching Nova launched a cloud of torpedoes towards the frigate. Interceptor cannons fired as soon as the projectiles were in range, and the space in front of the ship lit up with exploding warheads, the alien weapons detonating with eerie green blasts. The few torpedoes that got through the barrage were picked up by turret lasers as they passed through the outer edge of the frigate's shields, the brief flare of the shields providing markers for the ship's targeters. Nova returned fire with her two forward lances, hitting one of the attackers on its left engine. No shields absorbed the blasts, but it seemed as if the energy merely disappeared into the hull, leaving it unscathed.

The third ship had avoided the fight, and was nearing the station. It too fired torpedoes as it approached, but the volume of interceptor fire from the station's many banks of cannons made sure none of them got through. Having seen the resistance of its counterparts to the frigate's lances, the computer controlling the station's weapons targeted every lance at its disposal on the incoming ship, firing in a massive blast of light. There was an explosion on the ship's hull, but it came flying through the cloud of fire, its right engine torn open but still functioning. It fired another spread of torpedoes, following them with fire from its energy weapons, crackling beams of purple electricity, and the station's hull shielding lit up as the attacker began to have an effect.

"We have to close the Gate," said Vail on the bridge, watching the holoscreen as her ship and the station fired again and again into the enemy ships. It seemed that only a massive concentration of weapons had any effect at all on the strange lattice hulls of the ships. "Princess, what's the closure scenario for the Gate?"

"None," answered the computer.

"The what?" asked Liela.

"Most warp gates have some sort of system ready to close them if they become a risk. I suppose no-one thought that would happen here."

"What do we need?"

"It's usually a fusion bomb, detonated at the mouth of the gate. It does something to the warp energies holding it open, I'm not sure exactly. The result is the warp gate collapses."

"Doesn't your ship carry fusion bombs?"

"Only for specific missions. Not now." The bridge shook as a torpedo impacted somewhere below. The computer announced that it was increasing local shielding to compensate for the loss of armour.

"What about the reactor?" asked Liela.

"What? How?"

"A space station has to have stabiliser jets, doesn't it? In case of a collision, it has to be able to stop itself being moved out of position."

"Right," said Vail, thinking desperately. "Start priming the reactor to overload. I'll have Princess open up the access codes. Princess," she continued, looking up out of habit, "activate whatever thruster systems the station has, project best course to place the station reactor inside the detonation radius of the Gate."

"Course plotted," replied the machine's voice, "thrusters linked to reactor."

"How much power is there?"

"Reactor at one hundred percent."

"Engage." These was a rumble as the thrust of the long-disused rockets passed through the structure of the station. Vail grabbed the command chair to keep herself upright, while Liela braced herself in the seat she was currently using, keeping one hand at work on her console, instructing the reactor's output control systems to purposefully fail.

"Three hours to optimum detonation position," reported the computer as the acceleration settled down to a constant downward motion. It felt as if the station had lost a fraction of its gravity, but the movement was painfully slow.

"Three hours," repeated Liela, "I don't know if we can last that long. Shields are failing all over the cargo decks."

"Look," said Vail, staring at the holoscreen showing the space around them. A new ship had appeared, far off above the station. Liela looked up as the computer enhanced the image of the new ship, bringing into focus a sleek, streamlined shape, like an Imperial warship that had been built to move through water instead of space.

"Thunderchild," said Liela, "she's the fastest we've got. The rest will be somewhere behind her."

"Does she have teleporters?" asked Vail.

"Of course."

"Then lets get out of here. I don't want to be here when that reactor detonates, and she won't be able to teleport anything once her shields start taking hits from those ships. Princess, set all weapons to intercept incoming warheads, and divert all excess power to shielding the reactor and the interceptors. Do not fire on ships that aren't targeting the station, defensive fire only. Make course corrections if necessary. Your priority is getting the fusion reactor to the detonation position. You'll have to stay with the station until the end."

"Confirmed, orders initiated," replied the computer in its usual level voice. Vail watched the defensive systems update, took a last look at the small machine controlling it all, then turned to Liela, who activated a communications console.

"Thunderchild, this is rogue one," she said into it, "immediate teleport of two from station bridge. Clearance code Illumina. Confirm."

"Rogue one, code verified, teleport ready," came a voice from the distant ship. "Drop shields as soon as you can."

"At this distance?" asked Vail. Liela nodded and crossed the bridge to the shield controls.

"Which one of these controls the bridge shields?" she asked. Vail leaned over her shoulder and tapped in the command. Instantly, the bridge shimmered out of existence.

Not knowing what to expect, Vail was slightly dazzled when she found her new surroundings to be a shade brighter than the half-lit bridge module of Ascension. She had expected a chamber similar to the teleportaria fitted to Imperial vessels, but a quick glance around told her that she was more likely standing on the bridge of this ship, the Thunderchild. She had heard the name, in reports and orders sent out to all Inquisitors some time ago during the brief war the Imperium had waged against the elusive rebels, the Furies, but having been more concerned with events in the Segmentum Solar she had not made any further inquiries. Liela had taken a step towards a group of officers and was recounting the events of the past few hours, so Vail took the opportunity to take in her surroundings.

Although it was quite unlike any Imperial ship she had been on, it seemed certain that this was the bridge, not only because of the concentration of people who, she guessed from their rank insignia, were command-level officers. She and the assassin had materialised on a wide walkway overlooking what appeared to be the main deck of the bridge chamber. At either end of the walkway a stairway coiled around a clear cylinder containing what she took to be a single-level elevator, both currently resting at the bottom of their shafts. There were several duty stations visible on the deck below, all facing towards a wide couch which incorporated a number of viewscreens and controls - Vail took this to be the command chair, guessing the extra places were to accommodate a second-in-command and one other, a tactical specialist perhaps.

Her eyes were dragged away from their study of the workings of the bridge by the main screen, which stretched to either side of the chamber, and from the floor to the slightly domed ceiling several metres above. Surprisingly, Vail saw no distortion of the image from the edges of the screen, despite the angle from which she was looking. Some sort of holographic display, she guessed, and concentrated on what the screen was showing. On orders she had overheard from the officers clustered around Liela, the ship had swung around to shield her own frigate from the alien attackers. They in turn seemed unsure of how to respond to the new threat, which Vail attributed to the unfamiliar design of the ship. The Admiral had probably provided them with enough information to recognise most Imperial warships, but this was sufficiently different from anything they might have been shown to cause them to back off, if only for a moment. Behind them though, the mouth of the Volcano Gate threatened to release more attackers at any moment. Perhaps they were only waiting for reinforcements. Vail looked up and to the side, searching for the bulk of the station. From this distance it seemed that it has not moved at all.

"Inquisitor Vail?" said a voice from behind her. Vail turned to face the speaker. "I'm Commander Warfield," she finished.

Vail hadn't expected her to be on board, as she remembered from a report she had read that the leader of the Furies had kept that chapter's flagship, Artemis, as her own since their split from the Imperium. Presumably, though, she wanted to be first on the scene, hence her presence here on what was, according to Liela, the fastest ship available. Caught off-guard, Vail hadn't really been expecting anything when she turned to face the voice behind her. Given time to anticipate, she would probably not have expected what she saw anyway. Warfield was not particularly tall, although the presence of several true marines behind her made her seem slightly smaller. She wore a variant on the uniform that most chapters used when power armour was not necessary, although - naturally - the Imperial eagle was missing from its regulation place on the collar. Her face seemed quite at odds with the reputation she had acquired among the Inquisitors who were highly-ranked enough to know of her. The reports spoke of a uniquely powerful warrior, a fierce amazon, a strategist the equal of all those sent against her and a fighter skilled enough to challenge the best the Adeptus Astartes had produced. She looked less than thirty, too young to be everything she was said to be, and her face seemed somehow innocent, possessed of the glow that so often disappeared once the wearer of the face had experienced war first-hand. Vail met her eyes, and her doubts disappeared. Yes, she thought, this could be the one that Terra called the Huntress. There was power there, enough to fight the galaxy to a standstill if need be, but her ocean-blue eyes had a gleam that marked her as one of those rare leaders who truly cared about the lives of those she led. Despite everything she had been told by Terra - some of which she had doubted anyway - she knew that this was no predator. But, Vail was acutely aware, she was still the target of a standing order of Exterminatus, along with her entire chapter and fleet, an order initiated and, whenever opportunity had presented itself, pursued by the Inquisition. Would she trust an Inquisitor?

"We have quite a situation here," she began. "I have no doubt these 'Outsiders' will be attacking again shortly, but our arrival seems to have created a temporary cease-fire. Now, what I need to know is, where do you stand?"

"I am loyal to the Emperor," answered Vail. She stressed the name, recalling her earlier words to the assassin on the subject.

"So I hear," said Warfield, "but which one? We have the Emperor, a great leader who sacrificed himself to save his people, and we have the Emperor whose name is invoked to legitimise the feudal rule of the High Lords of Terra. I assume from your unique place within the Inquisition," she said this with a quick half-smile, "that you do not fully subscribe to the laws of Terra as they stand. Unless the Inquisition has started recruiting women while I was away? But this is not the matter at hand. What concerns me in the immediate situation is Order twenty-eighteen." Vail recalled the number, one of the standing orders issued by the Inquisition. In the situation she found herself in, she was required to do all in her power to damage the people whose aid she now needed. She was silent for a long moment, pondering the consequences of her actions here. For nearly ten years she had been an Inquisitor, dedicated to protecting humanity. So often, though, she had found herself having to step outside the boundaries of her position, having to bend the rules, because it seemed that if she didn't then she would somehow be failing the people she had sworn to protect. This was beyond bending the rules. If she failed to follow her orders now she would be an outcast, and everything she might achieve in the future would be lost. Were these really the enemies of humanity?

That was what it had always been, she realised. No matter the consequences to herself, she had never turned away from the path she believed in merely because it would be easier to do so. How many times had she been reprimanded, passed over for promotion despite her record, transferred from one sector to another without official reason, just because she had offended the wrong Lord, dug too deep in an investigation, found the wrong results when her superiors would have preferred an easy answer, be it true or not? And all to answer a cry for help, somewhere where no-one watched or cared, where there would be no recognition, no opportunity for advancement, no benefit in reaching into the dark corners of the Imperium and offering a hand to those whom she had no reason to help beyond the fact that if she didn't, no-one would. How could she praise the greater good while accepting the lesser evil?

"I don't recall that order," she answered with a perfectly expressionless face. A moment of understanding passed between her and the Commander, then Warfield turned slightly to indicate the screen, where Vail's frigate was keeping its distance from the Outsiders and the Thunderchild.

"You might want to inform your crew of that. If this little war starts up again they'll be caught in the middle." She offered a communicator to Vail, then nodded to another officer. The voice of Vail's captain echoed across the bridge.

"This is Nova, go ahead," he said, giving nothing away. Without knowing the situation, he was falling back on procedure, but, Vail was glad to see, not endangering the ship by doing anything stupid. Like following orders, she thought to herself.

"Nova, this is Vail. Code Siren, I repeat, Siren. This vessel and its allies are not hostile. You are to co-operate with them until I give you further orders. Your priority remains the defence of the station until it reaches the detonation zone." She paused, wondering what the captain would do. She knew him well, had chosen him specifically when she had been given the Nova, but this was uncharted ground for him and the crew.

"Thunderchild, this is Nova. We stand ready to assist you." Vail allowed herself a small smile. She turned slightly to see Liela at her side again.

"What does Siren mean?" she asked. "I thought I knew all the Inquisition codes."

"It's a private signal," said Vail, "it means that I actually want him to follow my orders instead of assuming I was being held against my will and opening fire."

"Always anticipate your enemy's next move?" asked the assassin. Vail nodded.

"In a way. The trick is to know who will turn out to be an enemy. And," she added, glancing at Warfield, again talking to her officers, "not to make an enemy out of a potential ally."

"Commander," called one of the junior officers on the deck below, "the psi-scanner's showing movement in local warp." Warfield tapped Vail on the shoulder of her armour, and the Inquisitor followed her down to the deck.

"How many?" Warfield asked, glancing at one of the screens which stretched around the perimeter of the bridge. Being unfamiliar with the design, Vail could only piece together events from the conversation.

"At least five," said the officer, "maybe as many as twenty. The scanner's having trouble seeing through the Gate's standing wave."

"It looks like we'll be resuming sooner rather than later," said Warfield, turning towards Vail, "we had been tracking a large fleet moving in towards the Gate on our way here." She led the Inquisitor to the command stations and offered her the seat on her right. Vail noticed that the controls on the Commander's seat had become active, where previously the screens had been blank. Those arranged around her own position remained inactive. Warfield touched a control on the armrest of her seat.

"Engine room," she said. A moment later a voice emerged from the control panel.

"I saw them," it said, "you have full power. I'll be there in a moment." Warfield nodded and turned her attention back to the immediate problem on the main screen. The three ships stood their ground as before, the one that had been damaged in the centre with the two others, seemingly intact despite Nova's best efforts, on its flanks. They had not moved at all since the end of the first battle.

"Contact established with the fleet," reported another officer, handling what looked like a communications console. "First battle group will be here in ten minutes. The Pallas Athena, the Castalia and the Sarpedon. Still no contact with the hostiles."

"We have ships within the Gate," called the officer whose report had brought the command staff back down to the bridge deck a moment ago, "eight cruiser-size ships, defensive formation." As he said this, Vail saw movement on the screen. She turned to see the three Outsiders accelerating towards them. Warfield had seen it too, and had already begun to command her ship.

"Helm, attack pattern alpha. Weapons, target the central module, no fire until I give the order. Torpedo guidance to automatic, raise shields to full power. You saw them using torpedoes?" she said to Vail. At her nod, the Commander leaned back towards the defensive systems station she had been addressing. "Bring the particle shields online."

The three attackers ignored the frigate, heading straight for Thunderchild. The damaged ship, in the lead, fired its torpedoes as it had done before, but the warship spun like a fighter, rolling over the path of the warheads. The other two ships pointed their noses upwards and fired, the combined cloud of torpedoes covering too great an area for the ship to avoid them again. Beams of light flashed from the forward hull, carving a trail of explosions through the torpedoes, but they left several to streak in towards the ship's hull. Vail braced herself for the impact, but the blasts as the warheads struck seemed to cause no damage. She heard one of the crew report minor power drain to the particle shields, and realised that the capabilities of this ship's shields extended past those of the energy fields used by Imperial warships. No wonder the Imperial Navy had called off their first seek-and-destroy campaign.

If the attackers were surprised by the lack of damage they didn't show it. Instead they continued to charge forwards, letting loose a barrage of energy that leapt from their weapons modules and crackled across Thunderchild's shields. One of them curved away from its attack run when Nova, silently turning in behind it, fired all her lances into the back of its engines, causing it to shudder visibly as arcs of power played across its hull. Whatever damage it suffered was not critical, as it righted itself quickly and turned to face the frigate. The other attacker cut beneath Thunderchild, firing up into the belly of the ship, but it found the shields there as efficient as those on the warship's prow.

"That's interesting." said a voice from the seat to the left of the Commander. Vail had been watching the first attacks so intently she had not noticed the new arrival, a young woman in her mid-twenties who was replaying the firing of the Outsiders' energy weapon on one of her screens. Warfield had glanced over at the screen, and Vail's eye, trained to notice details, caught a moment when their hands touched briefly, and for an instant their eyes brushed over each other. Then the newcomer returned to her screen, and the Commander turned back to Vail.

"Alisha Selene, our chief engineer," she said, by way of introduction.

"Hello," said the engineer without looking up from her screen. The ship shook as two of the attackers swung around and let loose another barrage of energy against her shields. "Some sort of forced matter stream," she continued, "carrying a type of plasma blast. Not unlike a Scorpion's blaster on a much larger scale. Give me a moment, I think the shields can be modulated to take the impact a little better."

Vail's attention, along with that of the rest of the bridge crew, except Alisha who remained at work, was drawn to the main screen again as the Gate swelled, its surface suddenly disturbed from below. A ship burst free of the red energy sea, larger than those already fighting, built along the same general lines but with more power, more weapons, thicker armour. Clearly a battleship. No sooner had it cleared the Gate, than a mirror image of it began to emerge.

"Relay orders to the first battle group," said Warfield, "tell them to come in firing. Weapons, commence fire. Target the damaged one first."

As if finally pushed too far, Thunderchild ceased her evasive manoeuvres and spun to face her attackers, the three already pounding her shields. Lance beams leapt from beneath her smooth hull, the main cannons fired a series of energy bolts, and two waves of torpedoes launched from beneath the prow. The Outsiders had not been expecting the sudden change, and the damaged ship was caught in the fire of every weapon. As before the lances seemed to melt harmlessly into the ship's hull, causing only a minor ripple, but the cannons struck the central weapons module without interference, exploding on impact and tearing open the alien ship. A moment later the first wave of torpedoes flew through the jagged hole carved by the station's lances, causing internal explosions that threw the ship sideways, trailing blue fire as its damaged engine gave up and collapsed. The second wave of torpedoes merely completed the task, blasting the weapons module to pieces and separating the two engines, the undamaged one spinning off harmlessly, the other continuing to disintegrate. The newly arrived cruisers accelerated towards Thunderchild as the remaining two raiders pulled back, now wary of the capital ship's power.

"Launch fighter drones," said Warfield calmly as the cruisers opened fire, carving trails of fire across her ship's shields. "Are those lances doing anything?"

"It's something in the hull design," muttered Alisha, "they seem to dissipate the beam and absorb the energy. It may even go back into their reactors."

"We're giving them power by firing on them? We can't afford to lose the lances, they're the only continuous fire weapon we've got. How did the station lances damage that ship?"

"Volume of energy, I think. Their system probably couldn't handle the amount of incoming fire, so it overloaded and the remaining energy," she paused as the bridge shook from a barrage of energy the cruisers had hit Thunderchild with, "cut through the hull as normal. I think we'd be better off trying to stop it from being absorbed in the first place."

"No time like the present," commented Warfield, turning to the weapons control station and indicating one of the cruisers on the main screen, which became the target of renewed fire from the main turret guns.

"Give me two minutes, I'm sure I can do something with the beam waveform. Could you fire a couple of low-power shots into one of them? I need better readings on the absorption." Warfield nodded to her first officer, who stood at a secondary tactical station. The ship let out a series of quick lance bursts at the nearest cruiser, none of them so bright or powerful as the first shots.

"Good," said Alisha to herself, "working on a formula now."

It seemed for a moment she would not have the chance, as more cruisers began to emerge from the Gate. Thunderchild's manoeuvres became tighter, as the greater presence of the cruisers began to cut off avenues of escape. One of them, the leader perhaps, although it seemed quite identical to the others, raced ahead of the pack, launching torpedoes from point-blank range and following them with a blast of its energy weapon. The bridge lights dimmed as power drained into the shields, and the crew had to hold their stations in order to prevent themselves falling when the deck shook beneath them. Two more cruisers came in from the sides, torpedoes firing.

A moment before they reached effective range for their energy blasts the ship to port of Thunderchild was rocked by an explosion on its side. Vail looked up, as if she could move the image on the main screen by force of will, but a moment later the source of the attack came into view. Three ships, Imperial Astartes cruisers, swung down to fire again into the suddenly vulnerable Outsider cruiser, breaching the hull of its left engine. As the ships passed by Thunderchild, Vail saw they were different from the standard marine warships. Apart from weapons similar to those on Thunderchild, each one had two armoured cylinders alongside its main hull, the hyperlight drive that had so enraged the Mechanicus and the Navigators when it became obvious to them that it was more than a wild rumour. One of the marine cruisers broke from the group and steered alongside Thunderchild, the remaining two curved in the other direction, firing torpedoes as they went, driving the Outsiders away from the Nova. Hopeful of a brief respite from the battle, Vail's hopes were dashed when a call from behind her announced the arrival of yet more ships from the Gate.

"We read them," said a voice from nowhere, which Vail realised after a moment was the captain of one of the newly-arrived ships, "Commander, we can't hold them here."

"Agreed," she answered, "pull back to five thousand kilometres and charge the drives. Try to draw them out away from the Gate. We can't let a battle develop around the station. Sarpedon, stay with Nova, she doesn't have our speed, if the enemy tries to attack stand between them. Castalia, be ready to move in at the first sign of an attack on the station itself. They seem to be steering clear of its defences for now." The captains relayed their orders and the ships began to move out, falling back in a rough perimeter around the enlarging alien fleet.

"They're moving to attack positions," reported the tactical officer, "targeting Sarpedon and Nova."

"Helm, move to intercept," ordered the Commander quickly, "don't let them get within range of the frigate. How many more," she began to ask, but was cut off by a blast that leapt from one of the alien cruisers, tearing across Thunderchild's shields. Some of the energy slipped through as the shields buckled, leaving a jagged line of black across the ship's hull armour. At the same time, in the distance beyond the alien fleet, a third group of cruisers emerged from the Gate.

"What was that?" said Warfield, without looking up from her console where she was programming a firing pattern for her ship's cannons. Alisha pulled a second screen to where she was working and studied it briefly.

"Plasma blast," she answered, "the large ships must have enough power to keep the matter stream coherent at long range. I think I've got a new waveform for the lances."

"Send to it weapons control," ordered Warfield, "relay to the other ships." The ship was rocked by a second blast as it closed on the nearest cruiser. This time the shields held, but only barely. "Hades with this," she said to herself, then raised her voice, "give orders for all ships. Shoot to destroy."

Sarpedon, still standing between the advancing Outsiders and the Nova, fired all her lances into one of the cruisers. At the same time Thunderchild fired hers, splitting her fire between the nearest cruiser and one of the smaller ships that had followed the attack. Sarpedon's target staggered under the assault, its hull flaring for a moment as it tried and failed to absorb the energy being poured into it. Half of its left engine exploded, throwing it wildly off course and into the path of its companion ship, which veered sharply upwards to avoid it. The damaged cruiser spun out of control, unable to stop itself, and began to break up from the stresses being placed on its hull. Thunderchild's target didn't last even that long: three lances converged at the same point on its central module, blasting it to pieces in an instant. The explosion severed the connection between the two engines, which detonated a moment later as they lost control of their containment fields, the power of the main drives suddenly blasting the hulls apart from inside. The smaller destroyer swung out of the way of the lances, but one of them caught it on the edge of its right engine, knocking it off course. A second volley of fire caught it in before it could regain control, and it shattered from the blast, its atmosphere burning up in a brief flare of bright blue.

"Commander, one of the ships is heading away from the Gate," reported the officer manning one of the sensor stations. Vail saw the ship, as its image was enhanced to full size on the main screen. It looked built for speed, four engines instead of two, with the weapons mounted along the sides of its hull instead of the centre. Not built for attack, but to defend against it. It was accelerating with unnatural speed, leaving the Gate and the rest of its fleet behind, heading for the open space created by Thunderchild's move towards Sarpedon.

"Intercept," called the Commander. She looked back up at the screen, at the same time as Vail realised the intent of the fast-moving alien.

"A scout," she said, more to herself than anything else. Warfield heard her, and turned. "They want to return to their homeworld," explained Vail, "where they were exiled from. They're trying to find out how well defended it is. That would tell them how much damage they can afford to take here."

"There isn't anything in Imperial records to match those ships," said Alisha.

"There are entire sectors near the core that haven't been explored by the Imperium," countered Warfield, "There must be dozens of civilisations there. How long until intercept?" she added, looking towards the helm station.

"The alien is still accelerating. Approaching point five cee."

"That's fast, for a conventional space drive," thought Alisha out loud, "it'd take us an hour to get that much speed on ion drive alone."

"Point six," read off the helm officer.

"Go to hyperlight, standard by five," said Warfield calmly. The main screen showed the stars ahead of the ship suddenly blaze, forming a massive, brilliant light that obliterated all detail from the screen. After a second the screen switched to an artificial image, generated by the tactical systems. Thunderchild was catching the alien scout, but not quickly.

"They're approaching light speed," said Alisha, her voice carrying a little wonder at the idea.

"How? Are they getting relativity effects?" Warfield asked the question at the same time as it ran through Vail's mind. She had little experience with the technical details of spaceflight, but she knew enough to be surprised that the alien ship could manage the sort of speed it had achieved.

"They're still running at normal time, according to our scans of their engine cycles. There's something strange about the field their drive is putting out, it's bending space somehow, I think they might..."

"Target has passed light speed, still accelerating," called out the helm officer.

"How is that possible?" asked Vail. Warfield looked genuinely surprised.

"I know how we do it," she said, "I don't know how they're doing it. Helm, hyperlight velocity at your discretion, catch them." The ship rumbled as power surged through its engines, and it leapt after the retreating Outsider, which in turn increased its rate of acceleration, its twin drives glowing with power.

Captain Tigrus frowned as another squadron of the alien cruisers appeared, immediately turning to head towards those already attacking the Furies. His own heavy cruiser, Pallas Athena, was beginning to show signs of the demands the battle was placing on it. At the moment her shields were still regenerating faster than the aliens were blasting them down, but if many more ships arrived that would change. Thunderchild's departure in pursuit of the scout had stretched the small fleet's perimeter too thinly, with only three ships, plus the slow-moving frigate, to keep the increasing number of aliens from escaping. Tigrus shielded his eyes as all of his ship's lances fired, vaporising the engine of a cruiser that had begun to bombard them.

He had just begun to order a new attack pattern when his sensor officer informed him of a new ship coming out of the Gate. Since this had been happening with distressing regularity for the last hour he knew that it had to be something unusual, or it would not have been reported. The new arrival dwarfed even the cruisers that had preceded it, its hulls towering over them as if they were mere fighters alongside their carrier. The dreadnought did not turn to approach any of the Fury ships; instead, it turned its attention to the nearby station, launching hundreds of torpedoes as it closed.

"Helm," yelled Tigrus over the noise of shield impacts from the cruisers still attacking his ship, "attack pattern on that ship exclusively! Put us between it and the station if you have to!" He turned to his weapons officer as the view on the forward screen tilted sharply, the ship veering upwards to evade the cruisers that were blocking its path. "Status of the station's defences," he demanded. The officer looked worried.

"Not good," he replied, "there aren't enough interceptors to take down so many warheads. Torpedo impacts on the cargo bays, some damage to the weapons platforms. Sir, they're firing on the reactor!" Tigrus turned, half expecting to see the station disappear in a nuclear blast, but the alien ship's energy blast merely burned a few layers of radiation shielding away.

"Low power?" he asked. His question was answered a moment later when the dreadnought fired again, this time vaporising a hundred square metres of armour, exposing the inner workings of the power plant and blasting away the damaged communications antenna. "Get us in there, full speed!" he ordered. With as much speed as it could manage among the alien fleet, the Pallas Athena swung down to stand between the dreadnought and its target. Without pause, the massive ship targeted the Fury cruiser, blasting at its shields.

"Captain," called one of the engineers on the bridge, "our lance power is insufficient to destroy them before they damage the station's reactor. Either it'll detonate prematurely, or it'll meltdown without a blast."

"Right," said Tigrus, crossing the bridge in a few quick strides. "Lieutenant," he said to his second in command, "you have the bridge. Protect the station. I'll lead our troops in an assault. I want to know where that thing's bridge is by the time I reach the docking bay." He left the bridge with an expression his subordinates were familiar with: the one that said he'd had enough, and someone was going to answer for it. Exactly five minutes later, amid the irregular light of energy blasts impacting on the ship's shields, a flight of Thunderhawks left the docking bay at full speed, manoeuvring wildly to avoid the swarms of torpedoes shooting around them, heading for the dreadnought. The tiny ships seemed to pass unnoticed by the massive warship as they closed to teleport range.

Tigrus materialised, alongside five of his most trusted warriors, in what his officers had guessed to be the bridge of the dreadnought. It may have been so, but Tigrus was unable to tell. The chamber was low, irregularly shaped, coloured in reds and oranges. Alien machines twisted up from the floor, as if they had grown instead of being installed. Were it not quite clear that everything around them was metal, Tigrus might have thought he was in a Tyranid hiveship. The floor was glowing, giving the chamber a soft illumination that, to his human senses, was directed in exactly the wrong direction, giving a sinister look to the shapes about him. Besides himself and his warriors, Tigrus shared the chamber with roughly two dozen aliens, each one humanoid but also vaguely insectoid. There was the suggestion of a carapace to their forms, which were covered in an assortment of materials, predominantly metallic, and their hands seemed to be descended from claws, though their fingers moved quite easily, not restricted at all by their shape. They seemed, so far as it was possible to tell from their flat, mantis-like heads, to be surprised by the arrival of the Terminators. Tigrus had only a second to observe all this, because after that the chamber, along with its crew, erupted in a hail of explosive bolts from the squad's storm bolters. Pushing curiosity to the back of his mind, the captain crossed the maybe-bridge to what appeared to be a door, and kicked it open, firing into the room beyond without waiting to see what it was. He and his squad quickly moved away from their teleport point, intent on causing as much havoc in the alien ship as possible.

"Brother-captain," a voice said from inside Tigrus's helmet. His autosenses dimmed down the noise of the assault cannon beside him for a moment as he replied. It was Vance, one of the half-dozen sergeants who had been on Pallas Athena when it had been called to Ascension. "We've found something that looks like a reactor of some sort..."

"Meltabomb the damned thing," replied Tigrus, "and keep watch. Teleport out if the blast is too much." Vance acknowledged the order. A moment later the floor-light flickered, then cut out completely. A low rumble echoed through the suddenly dark corridors, which were now lit only by the flashes of the storm bolters, and the occasional burst from the assault cannon. At his order, the Terminators switched on the spotlights mounted on their armour, which to the captain's eye provided a much more agreeable style of lighting. He began to settle into a rhythm, move, blast anything that fought back, and move again. In the back of his mind he kept track of the incoming messages from his ship, which were penetrating the dreadnought's armoured hull with only a little static. The ship they were in was still fighting, but as far as Pallas Athena's tactical officer could tell its firing had become uncoordinated, doubling up on some targets, ignoring others. Best of all, it had ceased its attack on the station, and its gunners were now concentrating on the more immediate threat of the heavy cruiser tearing holes through the sections that weren't under attack from within.

Tigrus knew that was the most important factor he had to consider - if the station's reactor were destroyed, no amount of fighting could stop the entire fleet from emerging into realspace and overwhelming the defenders. The Imperial Navy, which had begun sending ships towards Ascension at almost the same time as the Fury fleet had arrived, would not be in range of the Outsiders for two days. In that time, somewhere in the region of a thousand warships would have returned from the warp. Even accounting for the damage the Furies could do before they were overwhelmed and destroyed, the Imperial Navy battle group would suffer a similar fate if they engaged that many vessels in combat. And, thought Tigrus, that was if the Outsiders stayed and fought. If they chose to simply scatter among the local star systems, pillaging and moving on, the Imperium might as well write off the entire sector. The captain frowned at the thought, reloading his storm bolter for the fifth time as his squad cleared out yet another control room. Even now, according to the messages he was hearing from his ship, the tide was turning against them. Sarpedon couldn't leave Nova, or the frigate would be destroyed in seconds, denying them the use of her lances and torpedoes which, even without the Furies' drive to manoeuvre, had managed to account for a respectable number of ships. Castalia was practically surrounded, and had moved in towards the Gate, apparently reasoning that if she were going to be outnumbered, it would at least help to deny the enemy room to move. Pallas Athena was not faring well either, her particle shielding was flickering on and off from the volume of torpedo strikes it had endured. Maybe Lieutenant Commander Octavian, whose unnaturally accurate analytic mind was unfortunately half the galaxy away, would have been able to offer an estimate as to how long they could prevent the station being destroyed. Tigrus, who had always preferred to fight than study maps, could only keep attacking in the hope that they would buy enough time.

The scout ship had not slowed, nor had it shown any signs of doing so. Whatever it was using to achieve faster than light velocity served it well. To Vail's astonishment, and, it seemed, to the surprise of everyone else on the bridge, it had levelled off at somewhere in the region of eight hundred thousand times the speed of light. Alisha had admitted that not even the Thunderchild could maintain a pursuit at that speed for long. It came as a relief, then, when the alien vessel began to lose speed.

"Five minutes to intercept," called the helm officer. Alisha had noticed something on one of her screens, and was studying it with a frown.

"Star system in range," said the junior officer manning the sensor station, "some sort of interference with sensors. No information on star type or planets at this range. Six minutes to estimated planetary radius."

"They're going to beat us there," said Warfield with a frown. "We can jam their transmissions, so they can't report what they find."

"I don't think they'll be reporting anything," said Alisha, "the power from their engines is being shunted to another system. I think it's a weapon."

"How much power?" asked Vail, a suspicion forming in her mind.

"All of it, I think," said Alisha, "the star's interference is starting to distort readings, but it's a lot of power, that much is certain."

"A weapon," repeated Warfield, half to herself. "They're going to attack their own homeworld. They don't want to return to their race, they want to destroy it."

"Revenge for being trapped in the warp, for Emperor knows how long," agreed Alisha. "Assuming they fire as soon as they achieve orbit..." her voice trailed off.

"We're going to be too late," finished Warfield.

Tigrus slammed a meltabomb onto the casing of what looked like a power conduit, then turned and ran as fast as the ship's gravity would allow. Behind him the room he had barely left erupted, a wall of fire following him down the corridor. He rejoined his squad, who had gone on ahead of him and were gunning down what appeared to be guards. They were armoured at any rate, but aside from an attempt to gun down the squad with some form of rifles they seemed ill prepared for the Terminators, their weapons platforms lying half-assembled in front of their bodies.

"Status?" yelled Tigrus over the noise of firing, which was overcoming his autosenses ability to compensate.

"Massive power fluctuations in all systems," reported the Lieutenant on board Pallas Athena, "recommend immediate teleport."

"Do it!" Tigrus could feel the deck shaking beneath his armoured feet. He had a last glimpse of the corridor twisting under unimaginable stress, then it all faded into the glow of the teleporter. When the glow faded he was back on the bridge of his ship, rather than the cramped transport bay of a Thunderhawk. A quick glance at the ship's defence displays told him why - her shields had dropped, and now only armour stood between them and the alien fleet. On the positive side, such as it was, this allowed his troops to be teleported directly back to their ship, rather than having to take another perilous ride on the assault craft, where one stray shot would obliterate them without warning. He nodded to the Lieutenant, who vacated the command chair and began working with the engineers to restore at least some shielding. Tigrus was in no mood to sit, and in any case he was still wearing his Terminator armour.

No sooner had he retaken command of the bridge, another dreadnought appeared. It was of a different design to the one now a drifting wreck, but it was of similar size and, quite obviously, similar combat capability. Tigrus braced himself as it fired past them, offering a quick thanks to the Emperor for his helm officer's anticipation. If they had been hit, without shields, it would probably have been the end of them.

"Captain, the Castalia!" Tigrus had half-turned towards his Lieutenant, before his words sent him back towards the forward screen. Emerging from a cloud of alien cruisers, the Castalia bore little resemblance to the ship that had accompanied Pallas Athena into the battle. Its forward hull was torn open, twisted black wreckage where armour and weapons had once been. One hyperlight nacelle was missing, the connecting pylon shattered by repeated impacts from torpedoes. All across the ship's hull were the marks of battle, jagged slashes where energy blasts had penetrated the ship's armour and ripped into the decks below. The bulk of the ion drive, scarred but still operational, was pushing the ship towards the new dreadnought. Tigrus pushed his communications officer out of the way and opened a channel to the dying ship.

"Seldonas!" he called to the captain aboard her - the bridge, miraculously, was still intact. "Get out of there!" A crackle of static was all the answer he got. "All teleporters, get them off that ship!" His crew began to report the status of the teleporters as they pulled any living being away from the Castalia. The numbers were called off as the teleporters worked, twenty, forty, a hundred, but it would not be enough. With a final burst of speed, Emperor alone knew how they had managed to get it out of those engines, the ship ploughed into the side of the dreadnought. The prow, already weakened, seemed to fold in on itself, but each piece of debris was a massive bulk of metal, tearing into the alien armour. When the bodies of the two ships met, there was a massive blast of light. It cleared to show the remains of Castalia's ion drive tearing through a massive hole in the dreadnought, which had begun to break in two, its forward hull tilting sideways, tearing away the internal supports that bound it to the rear sections. One of the engines, severed neatly by the impact, exploded, throwing wreckage in all directions, completing the task of destroying the alien ship as well as battering at the several cruisers who had tried to follow Castalia in her suicide attack.

Tigrus watched with horrified fascination as the light from the impact faded, the wreckage spun slowly off into the void. For a second everyone was silent, even the battle seemed to pause in the aftermath of the destruction. Then a voice behind him spoke. Tigrus turned his head, keeping his eyes on the screen, and he only registered the meaning of the words when they were repeated: 'detonation zone.' His eyes slid away from the fading light of the explosions to the Gate, and the dark bulk of Ascension station hanging over it, closing so slowly it seemed immobile. Energy was crackling across its fusion reactor, which was pointed directly at the mouth of Volcano Gate.

"Hyperlight!" barked the captain, even though his officers were already in motion, "get us out..." Then the world turned white.

Pallas Athena raced ahead of a wavefront of pure energy, the release of the unimaginable forces that had, for thousands of years, held open a gateway to the warp. In the distance, barely visible, the Sarpedon accelerated, holding Nova in a tractor beam. Both disappeared in their own tiny flashes of light, invisible next to the brilliant glow of the exploding Gate. The alien ships, unable to accelerate so quickly, were not so lucky. One by one the wavefront overtook them, consuming each one in turn in a sea of energy, leaving no debris, no trace. Finally, almost half a light year from the original position of the Gate itself, the wavefront slowed, stopped, then began to recede. To the observers on the three ships that had escaped, it was as if the ball of light, larger than even a star system, snapped back into itself like a balloon stuck by a pin. Growing ever more brilliant as it compacted, the sphere closed in on itself, remaining for a moment as a new star in the void before simply disappearing, like a light turned off. With it gone, there was nothing. Of the remains of the Outsider fleet, Ascension station or the Volcano Gate itself, nothing remained but empty space.

Thunderchild flashed into existence barely ten kilometres from where the Outsider scout had come to rest. Close enough to cut through the interference from the star, the main screen showed the massively-engined ship drifting above a wide asteroid belt that stretched around the system. Its engines were dark, and there was no sign of the weapon it had been preparing to use.

"Scan," said Warfield, her voice low, as if reluctant to startle the motionless alien ship, "those asteroids..."

"They were a planet," said Alisha, "but that ship didn't destroy it. By the look of their orbital pattern, the planet was destroyed somewhere above fifty thousand years ago."

"They were trapped for that long," said the Commander, staring at the ship in the screen.

"They avoided the destruction of their world," countered Alisha. "But they can't punish a dead world." Warfield had stood and approached the screen, and she now turned back to face the bridge. As she did so the screen was lit by an explosion. Whirling around, expecting to feel the deck rock under her feet, she saw only a ball of fire where the scout had been. The afterimages of its destruction faded from the screen, replaced by a cloud of debris, spinning outwards. Warfield turned again, her face asking the question, 'why.'

"I think I know," said Vail. "All they wanted was revenge. They must have survived all that time because they hoped they'd have a chance to deliver it. But they just found out they couldn't. It must have felt like they had nothing to live for." Warfield looked at the Inquisitor for a moment, then nodded and resumed her seat.

"What would they have done," she said softly, "after they had taken their revenge?"

"I don't know," said Vail, looking at the belt of asteroids orbiting the distant star, "maybe they didn't either." Warfield let out a sigh, still watching the screen.

"Such a waste," she whispered to herself.

"Report coming in from the Pallas Athena," called the communications officer, "the battle is over. The Gate has been closed, all alien ships destroyed in the blast."

"I wonder," said Alisha as Thunderchild turned and headed back towards the previous location of the Gate, "how many are still in the warp?"

"There must be some," Warfield said, "maybe hundreds."

"Do you think we'll have to fight them again?" asked Vail. Warfield thought for a moment.

"Maybe," she said at last. "Or maybe next time we won't have to fight. It'll be a long time before they find another way back to realspace. Maybe enough time for them to change."

Vail looked away from the viewports, open to space, and back around the conference table. She was at one end of it, at the other was Commander Warfield. Between them were Alisha, Liela, Captain Tigrus, who had only a moment ago teleported from his ship, Captain Cembera of the Sarpedon, and Lieutenant Chase, the second in command of the third company, one of the survivors of the destruction of the Castalia. Chase's captain, Seldonas, has stayed with his ship. From what she had heard, Chase would now become a Captain, and command the new Castalia when it was complete.

"Inquisitor," began Warfield, "now that the immediate threat is out of the way, we must decide what to do with you. Despite your actions in the last few hours, you remain a member of an organisation that is openly hostile towards us. I'm honestly not sure what to do."

"Commander, if I may?" asked Vail. Warfield nodded. "The order against yourself and this chapter is, as you recalled earlier, number twenty-eighteen. When I first became an Inquisitor I took a vow to uphold the orders of Terra, whatever the situation. Order one, the founding principle of the Inquisition, is to protect humanity. In cases where there is conflict between the orders, that overrules all others."

"But do you believe there is conflict?" asked Liela.

"I believe," answered Vail, "that it is in the best interest of humanity for a group such as this to exist. We saw as much today. The Imperium does not share my views, and would do anything in its power to destroy you. Therefore, in accordance with the First Order, I must do what I can to prevent this. An Inquisitor is given the power to take any actions they believe to be necessary to fulfil their orders."

"What you are proposing," said Warfield, "is that you become a spy."

"I'm an Inquisitor," responded Vail, "that's part of what we do. I'd like to do it for something I believe in."

"I know the value of belief," said Warfield after a moment. "I've been studying our information on the Inquisition, on you specifically, since the end of the battle. To put it briefly, I believe you." Vail smiled and relaxed in her chair. "I'm not saying we can just put you back on your ship and turn you loose. But it gives us new options to consider. Perhaps," she said, looking to Liela, "someone could accompany you, should you decide to take this role. For you, a partner, an ally. For us, a watcher."

"It's a reasonable idea," the assassin said, "it's what I've been doing anyway. And," she added, "you know there's no-one better qualified to keep track of a security risk."

"I'll take it under consideration," said Warfield. "Now, assuming I decide this is a good idea, can we install a drive in that frigate?" The question, addressed to Alisha, seemed to signal the end of the meeting. The captains stood, as the engineer launched into an impressive demonstration of how, as far as Vail could tell, installing such a drive was possible. Liela approached Vail, who stood to meet her.

"Hope you don't get tired of me looking over your shoulder," the assassin said lightly.

"At least you can watch my back while you're there," replied the Inquisitor.

"Inquisitor, a moment," said a voice from behind her. She turned to see Tigrus, the Terminator captain, looming over her. Even without his armour he was larger than a normal marine. "There is another matter, which I believe is to do with you. I spoke with Liela shortly before this meeting, and she assures me that this is yours." He held out a hand, and Vail looked down to see a slim, grey case, not much larger than a data tablet. "It was teleported from the station at the commencement of the detonation sequence." Vail took the computer and smiled.

"Thank you Captain," she said. She then raised the box in her hand, bringing it to eye level. "Princess?"

"Active," it said, causing Tigrus to react just the slightest.

"I don't remember," she continued, still smiling, "telling you to teleport yourself."

"Orders regarding the station had been completed upon initiation of the reactor overload. In the absence of further orders, the presence of this unit there conflicted with inbuilt self-preservation routines."

"Smart machine," said Liela. Vail nodded and returned the computer to its usual place in her armour. Tigrus returned to the other ship commanders, who had begun a private conversation in one corner of the conference room. Alisha was still explaining technical details to Warfield, her hands moving in complex patterns, demonstrating energy flows and engine structures.

"So, Vail," said Liela, "assuming we get clearance, where's our first mission? After we drop off the Admiral at the nearest penal colony?"

"Justina," said the Inquisitor.

"Where's that? Segmentum Tempestus, I don't think I've heard of it?"

"It's my name," explained Vail, "some Inquisitors have a first name, you know."

"Well I don't," answered Liela. "I can count myself lucky to have one. If I was a Vindicare, I'd only have a number."