'As soon as they can,' said the Lion. He strode towards the door. 'We cannot afford to arrive too late at Perditus.'

II.

Although almost as tall as the Legiones Astartes warriors with whom she travelled the warp, Theralyn Fiana of House Ne'iocene was far slighter, willowy of build with slender fingers. Her hair was copper in colour, as were her eyes; her normal eyes, at least. In the middle of her high forehead, from which her hair was swept back by a silver band, was her Navigator's eye. To call it an eye was to compare a glass of water to the ocean. This orb, translucent white but dappled with swirling colours, did not look upon frequencies of light, but delved through the barrier that bounded the warp, looking upon the raw stuff of the immaterial realm.

Now that warp-sight was employed moving the Invincible Reason away from the translation point at Balaam. The streaming threads of the warp currents were tugging hard at the ship, which sat cocooned within an egg-shaped psychic field, buoyed upon the immaterial waves like a piece of flotsam on the ocean tides. She sat in the navigational spire high above the superstructure of the battle-barge. Out of instinct, Fiana looked for the bright beacon of the Astronomican, and as she had done for the last two and a half years she felt a part of her soul grow dim at the realisation that it could not be found. That the light of Terra no longer burned had been a source of constant argument amongst the Navigators attached to the Dark Angels Legion, with Fiana amongst the growing camp who believed that the only explanation was that the Emperor was no longer alive. This was not a popular viewpoint, and one not to be raised with the primarch, but the logic was inescapable to Fiana.

In the absence of the galaxy-spanning Astronomican, the Navigators relied on warp beacons tiny lanterns of psychic brightness from relay stations in real space. They were candles compared to the star of the Astronomican, and only one in ten systems in the sector had them, but they were better than moving wholly blind; so much so that both the Night Lords and Dark Angels had tacitly agreed to treat the beacon stations as no-go areas. The risk of stranding one's own ships in the warp was too great to chance the destruction of the fragile orbital stations.

Perditus was not a beaconed system, and was located only one hundred and fourteen light years from Balaam, on a two-hundred-and-thirty-degrees, seven-point incline heading from the Drebbel beacon, which in turn would be found on a path at one-hundred-and-eighty-seven degrees, eighteen-point negative incline three days out towards the Nemo system. Glancing at a hand-drawn chart draped over the edge of her rotatable chair, Fiana confirmed this and examined the currents lapping at the barrier of the Geller field surrounding the Invincible Reason.

The warp did not look like its true state, even to her. Yet Fiana's warp sight allowed her to sense an approximation of its tidal powers and whorls of immaterial confluence. The Balaam system had been chosen for the rendezvous because from here a near-constant current ran through the warp almost as far as Nhyarin, nearly three thousand light years away. Nothing was ever certain with the warp, and its strange ways meant that sometimes the Nhyarin Flow ran backwards or could not be located at all, but eight times out of ten it could be relied upon to speed travel to the galactic south-west, fully across Aegis and two other subsectors. The worlds along its route were amongst the most hotly contested between the Night Lords and the Dark Angels.

Fiana punched in a series of coded orders for the piloting team situated in the command deck. A few minutes later, the Geller field bulged to starboard, its psychic harmonics adjusting to the controls of the crew so that the Invincible Reason edged out of its current course and into the outlying streams of the Nhyarin Flow. Psychic power gripped at the shields like waves tugging at a leaf, and though there was no real sensation of movement, Fiana felt in her thoughts the battle-barge surging ahead, flung forwards across time and space at incredible speed.

Around her, the pinpricks of light that had been the other ships of the fleet winked out of existence. Within half a dozen minutes, nothing could be seen of the flotilla, scattered to the four points of the compass and stretched through time by the eerie workings of warp space.

Turning in place, Fiana conducted a quick scan for storm activity. The whole of the warp was alive with tempests, but the Nhyarin Flow seemed stable enough for the moment. There was no horizon, no distance or perspective, and for just a moment Fiana teetered on the brink of being swallowed by the abyssal nature of the warp. She reeled her mind back into her skull, pulling down the velvet-padded silver band so that its psychic-circuitry-impregnated metal covered her third eye.

Just before her othersense was curtailed she thought she glimpsed another ship, riding on a swirl of energy behind the battle-barge. It was probably another Dark Angels vessel, caught by fortune on the same timeflow as the Invincible Reason. She made a note of it in her log and signalled for her half-brother Assaryn Coiden to ascend the pilaster and take over. As the senior member of the household, it was her responsibility to see that the ship was safe during transitions, but now that the task was complete, she was glad to be able to delegate to her younger siblings. Things were far more peaceful in her quarters, and ever since Horus's rebellion had begun and the storms had come, just an hour of exposure to the warp had left her with splitting headaches and a soul-draining fatigue.

There had always been talk amongst the household, of what the warp really was, and whispered stories of the strange phenomena that the Navigators sometimes glimpsed on their travels. Now Fiana was certain that there was something else out there; not just aliens living in the warp as she had been warned, but something that existed as part of the immaterium itself.

And the stories had grown in number, and in horror. Ships had always gone missing, but the frequency with which they were now lost was frightening, as if the warp itself was rebelling at their presence. Having felt dark swirls and malignant tendrils tugging at the edges of her thoughts, Fiana knew too well that the warp was far from a welcoming place.

The Lion's stare was cold as it fell upon the chief Navigator, Theralyn Fiana. This was the fourth audience in seven days that he had granted her, and twice also had he received representation from her through Captain Stenius. Her complaints were becoming tiresome, and made all the more irritating because there was nothing the Lion could do to alleviate the problems she and her fellow Navigators were experiencing. She had joined the Invincible Reason at Balaam, highly regarded as an expert of the warp tides they were travelling, but so far the Lion's only impression was of a thin-faced woman who had nothing but excuses to offer for their slow progress.

This time she had Captain Stenius for company, and looked even more agitated than normal. The Lion waved Fiana forwards with a gauntleted hand, suppressing a sigh of annoyance. The Navigator stopped five metres from the primarch's throne, the ship's captain a few paces behind. She was dressed in a flowing gown of green and blue, of a material that shimmered like water when she walked. Her bare arms were painted with rings of varying design from shoulder to elbow and the backs of her hands were tattooed with intricate intersecting geometric shapes copied by a cluster of pendants that hung on a thin chain around her neck.

Fiana's third eye was concealed by a broad silver band across her brow, but the Lion could feel its touch upon him, like a spark of heat on his flesh. Navigators, and all psykers for that matter, caused him pause; he was not well disposed to those who might see him in ways that normal men did not. Only the Emperor did he trust with such knowledge.

'What is it?' said the Lion. He fluttered a hand towards Corswain, who had just arrived and was due to brief his leader on the latest intelligence concerning Perditus. 'Be quick, there are other matters demanding my attention. If you wish me to still the warp with a wave of my hand, I must disappoint you again, Navigator.'

'It is on another matter, an urgent one, that we must converse,' said Fiana as she rose from her bow. She glanced at Captain Stenius and received a curt nod of reassurance. 'Lauded primarch, for the past several days, since we translated from Balaam, I and my family have witnessed a ship following in our wake. At first we thought it coincidence; a companion vessel of the fleet that happenstance had tossed upon the same course as ours.'

'But you no longer believe this to be the case?' said the Lion, leaning forwards. 'It is my understanding that it is extremely difficult, perhaps impossible, to trail a vessel in warp space.'

'That was our understanding also, lauded primarch. Many times have Navigators attempted to stay within reach of each other, but ninety-nine times out of a hundred all sight is lost within a day, and always within two days. We sometimes make analogy between the warp and the currents of the sea, but it is a simplistic comparison. The warp flows not only through space, within another realm beside our own, but also upon different streams of time.'

'This I know,' snapped the Lion, growing impatient. 'An hour passes in the warp and several days have turned in real space. If a ship translates a day before another, it could be weeks ahead in its journey. You have not yet explained why coincidence is not a suitable explanation, Navigator. I have made hundreds of warp jumps in my life; it is not remarkable that on one journey another ship might be caught upon the same current.'

'No, lauded primarch, it is not,' replied Fiana. She straightened to her full height and met the primarch's glare, though only for a moment before the intensity of his eyes forced her to look away again. 'It is remarkable that we have changed stream four times in the last five days, seeking the fastest current to Perditus, and within the hour the ship is behind us again. It is following us, lauded primarch, and I know of nobody who possesses that capability.'

The Lion did not waste time asking if she was certain; the forthright tone of her voice and hard look in her eye convinced him that she spoke the truth as she believed it. He nodded and gestured for Captain Stenius to step closer.

'I am sorry, Lady Fiana, for my curtness. Thank you for bringing this matter to my attention. Captain, I believe that you were already aware of this?'

'Lady Fiana brought her suspicions to me yesterday, my liege. I asked her to confirm her findings for another day and decided it was worthy of bringing to you.'

'It is an impossibility, lauded primarch,' said Fiana. 'No Navigator can track another vessel in the warp with such accuracy. We work on suggestions and instincts far too vague for such precision.'

No Navigator, thought the Lion, but not impossible.

During his infancy on Caliban, growing up alone in the dark, monster-infested forests, he had learned quickly that some beasts did not need to see to hunt. Some possessed senses other than sight and hearing and smell; they could stalk their prey by the spoor of their soul. Such creatures were the deadliest he had faced, not wholly physical. The knights of Caliban called them nephilla and it was only with great effort that they could be slain, though the Lion in his youth had killed several.

It was a stretch from nephilla roaming the dark forests of Caliban to a ship that could unerringly track another through the warp but, like Fiana, the Lion did not trust anything to coincidence. There were forces at play forces unleashed by Horus and his allies that he did not fully understand, and until proven to the contrary the Lion was willing to believe his foes capable of anything.

'For the moment it is sensible to assume that our mysterious pursuer is a Night Lords ship,' the Lion said after a half-second of contemplation. 'Do you think it is possible to elude this enemy without undue risk or excessive delay to our journey? I would not have the foe learn of our destination and the secret held there.'

'I am not sure I would know what to do, lauded primarch,' said Fiana. 'It is not something a Navigator learns.'

'Surely you have experienced pursuit by other than a ship?' said the Lion. 'There are denizens of the warp that are known to chase vessels.'

'Of course,' said Fiana. 'I know a small repertoire of evasive manoeuvres, but the usual response when facing such a crisis is an emergency translation into real space.'

'That will be our second option,' said the Lion. 'I would rather avoid the delay that would add to our journey. You have two days to shake our hunter. Report your progress directly to me, Lady Fiana.'

'As you command, lauded primarch,' said the Navigator, sweeping down into a long bow.

When Captain Stenius and Lady Fiana had departed, the Lion called to his seneschal to attend him.

'I am deeply suspicious of this craft that follows us, Cor,' the primarch said. 'Have the weapons crews sleeping beside their guns, and double the watch strength.'

'As you command, my liege,' said Corswain. 'If you have time, we should discuss the strategy you wish to employ when we arrive at Perditus. The last contact we have shows that the Iron Hands and Death Guard were just beginning hostilities. It is possible that one side or the other may have gained the upper hand since then.'

The Lion pushed aside thoughts of phantom ships and concentrated on the wider task.

'We treat Perditus as hostile,' he declared. 'It is impossible to say for which cause any other force fights. Death Guard, Mechanicum, Iron Hands: all are to be treated as enemy until I say otherwise.'

For two days Fiana and the other three Navigators aboard the Invincible Reason performed several manoeuvres that would, in normal circumstances, separate them from the following ship. They frequently changed flows within the warp, shifting the battle-barge from the fast-moving stream of the Nhyarin Flow to the more sedate currents that drifted from its outer edges. They dived into swirling eddies, a risky proposition even before the recent tumults that had engulfed warp space. Twice they turned the ship fully about and forged into counter-flows, taking them away from the route to Perditus.

Always the other ship found them again, sometimes never breaking away, other times vanishing only to appear on the edge of detection an hour or two later, following unerringly in the battle-barge's wake.

After the two days allowed by the Lion, Fiana and Stenius convened again with the primarch to discuss the next course of action. With the Lion was Corswain, summoned by his master. It was Stenius who spoke first.

'Whatever force guides our pursuer, it is beyond our means to shake them loose, my liege,' announced the ship's captain.

'Not wholly beyond our means,' said Fiana, earning herself a sharp look from Stenius; enough to betray the existence of a previous argument between the two, though his partial facial paralysis prevented any more meaningful expression.

'I will not risk my ship,' Stenius said flatly.

'You have an alternative?' said the Lion, directing his gaze to Fiana.

'Three days ahead, perhaps four, there is a well-known anomaly, which we call the Morican Gulf. It corresponds roughly to the Morican star, a dead system. There is a region that is like a gap in the warp, a bottomless gulf surrounded by a turbulent maelstrom. It is possible to run the outer edges of this whirl, and the storm should mask our departure route.'

'And the risks?' asked Corswain.

'The null space, the void in the eye of the storm, can becalm a ship, leave it stranded for days, for weeks, sometimes forever,' said Stenius, shaking his head in disapproval. 'It should not be considered at the best of times, and our mission at Perditus is too important to risk delays or worse.'

The Lion considered this, weighing up the merits of losing the pursuer against potential calamity. He disregarded the Navigator's plan, but remembered the earlier conversation he had shared with Fiana.

'Lady Fiana, you suggested before that we might make an emergency jump to real space. Is it possible that we could do so whilst the other ship has been blinded by one of your manoeuvres?'

'Possible, yes, lauded primarch,' said Fiana.

'There is no guarantee that our phantom ship has not the means to detect such a thing,' said Corswain. 'We have no idea of their capabilities. As I understand it, any translating ship creates ripples, an echo along the warp currents. If the Night Lords have a psyker or some other means to track our normal movements, a translation would be as clear as a summer day to them.'

'An emergency jump even more so, lauded primarch,' added Fiana. 'The backwash would be like dropping a boulder into a lake; even an inexperienced Navigator could detect it.'

'There is also the danger that our warp engine rift will collide with the Geller field of the other ship,' said Stenius. 'Whatever means they have to follow us, they have to stay close to use it.'

'Interesting,' said the Lion, a chain of thought set in motion by the Captain's warning. He looked first at Corswain and then fixed his eyes on Stenius. 'Little brothers, have the ship secured for an emergency translation, but keep the gunnery crews at their stations. Lady Fiana, I want you to position the ship in a particular way. Find a swift-moving warp current from which you can quickly move to a contra-flowing one.'

'What is your intent, lauded primarch?' asked Fiana, a worried frown creasing her pale skin beneath the silver of her headband.

'Our enemy shadow our movements closely but not instantaneously,' explained the Lion. 'We will move in such a way as to draw them extremely close, and then we will activate the warp engines to jump back to real space. The other vessel should be caught in our exit wake and drawn from the warp after us. In real space our enemy will become vulnerable to attack.'

'If both ships are not torn apart, my liege!' said Captain Stenius. He was about to continue his objections, but the Lion cut him off with a sharp gesture.

'You know my intent. The plan is not a subject for discussion. Lady Fiana, it will be up to you to choose the optimum moment for translation. From everything I have heard of your skill previously, I expect success.'

'Of course, lauded primarch,' said the Navigator, her face set with determination. Her reputation had been placed on the line, and for a Navigator aspiring to be the next Matriarch of her House there was no commodity more valuable than the praise of a primarch.

The Lion looked at Stenius and leaned forwards, his voice dropping low.

'You understand my orders, captain?' asked the primarch.

'I do, my liege,' Stenius replied quietly.

'Then you are both dismissed,' said the Lion. He reached a hand out towards Corswain. 'Stay a moment longer, little brother.'

When the ship's captain and Navigator had departed, the Lion motioned for Corswain to approach the throne.

'I am worried about Stenius,' confessed the primarch. 'At first he delays bringing the fact of our pursuit to my attention, and now he seems reluctant to resolve our predicament.'

'I am sure there are no grounds for suspicion, my liege,' said Corswain, affecting a formal tone, disquieted by the subject of Stenius's loyalty.

'Sure, little brother? One hundred per cent certain? You would vouch for Stenius yourself?'

Corswain hesitated at the challenge in the Lion's voice. After a moment, he lowered to one knee and bowed his head.

'I have no doubt about Captain Stenius, my liege. However, to allay any reservations you may harbour, I shall have Brother-Redemptor Nemiel report to you.'

'As you see fit, little brother,' the Lion said, offering a rare smile.

III.

The narrow chamber atop the navigational pilaster could barely hold all four of the Navigators. What the primarch had asked for required a very specific set of circumstances. Fiana and her fellow Navigators each surveyed a stretch of the warp, seeking the conjunction of flows needed to bring the Invincible Reason quickly back towards the phantom ship. All other preparations had been made; the ship's company were braced for the potentially devastating drop back into real space, while Fiana had warned her companions of the deleterious effect it could have on their minds.

'I have something,' said Ardal Aneis, Fiana's younger brother. 'A counter-nebulous promontory, on the port bow.'

Fiana directed her unnatural gaze in the direction Aneis had mentioned and saw what had caught his attention. Three warp streams, one very strong, the other two weaker but approaching each other at steep angles, came together to create a three-dimensional whirlpool. The outflow curved back over the battle-barge's path and intersected with a dead pool that slowly leached back into the Nhyarin Flow.

'Captain Stenius, please direct primary navigational control to my console.' The communications pick-up buzzed in Fiana's shaking hand and she resolutely avoided the concerned looks in the eyes of her fellow Navigators. She received the affirmative from Stenius and a few seconds later the screen below her left arm flickered into life. A diagnostic sub-routine scrolled quickly across the pale green glass and then the screen went blank.

Fiana's voice dropped to a whisper as she keyed in the manoeuvre required to plunge the ship into the heart of the promontory. 'Remember the pride of House Ne'iocene.'

There was no sound, in the warp. No real tidal pressures or inertia pulled at metal and ferrocrete, but even so Fiana could sense the tortured mass of the Invincible Reason as its Geller field realigned, shoving the battle-barge from one streaming eddy of warp energy into another. Fiana felt a moment of sickness as her othersense lurched and spun, while all around her, the clashing currents of the psychic promontory smashed together like the slavering jaws of an immense, immaterial beast.

Kiafan, youngest of her siblings, fell to his knees beside the chief Navigator, emptying the contents of his stomach upon the floor between snarled gasps of pain. Fiana ignored the distraction and keyed in another instruction on her runepad. The ship settled into a trough of psychic power for several seconds, before rising up, ejected from the promontory like a grain of sand caught in the spume of a breaching whale.

Fiana gritted her teeth and made a final adjustment to their course, forcing herself to peer along the unwinding threads of energy that unravelled before her. She anchored the Geller field onto the strongest and then pushed aside her companions to collapse into the only chair in the chamber.

'Captain, we are on our new heading,' she gasped over the comm. Steadying herself, she looked for the bobbing mote of energy that was the other ship's warp signature. She located it ahead, approaching quickly. There was no time to waste. Even from their prepared idling state, it would take several minutes for the warp engines to charge to full power. Any longer and they would be right on top of the phantom ship, their Geller fields merging. The effect of translating in such close proximity to another vessel would be certain destruction for both ships.

'Translate now, captain! Activate the warp engines!'

Trying to emulate the example set by his primarch, Corswain stood immobile on the gallery above the Invincible Reason's strategium, just behind and to the left of the statuesque Lion. On the other side of the primarch was Brother-Redemptor Nemiel. The Chaplain wore a skull-faced helm, so that nothing could be seen of his expression, concerned or otherwise. Lady Fiana's snarled command had not helped settle Corswain's mood, and had set the command crew below into frenetic activity. The navigation aides moved quickly from station to station in the bright glow of their screens, monitoring power outputs and safety thresholds as the plasma reactors of the battle-barge went up above one hundred per cent output in preparation for the warp engine activation.

Corswain clenched his jaw as he felt an ill-defined pressure building in his skull. It was not like a concussive shockwave or the pull felt in a plunging drop-pod, but more like a container slowly being filled, reaching its capacity and yet not bursting. The ache was behind his eyes, mental not physical. Aside from the brain-juddering dislocation of teleportation, it was the most unpleasant sensation he had ever encountered in his long years of service to the Legion.

A glance at the Lion confirmed that if the primarch suffered the same discomforts as his little brothers, he showed no outward sign of it. The commander of the First Legion stood with legs braced apart, arms folded across his breastplate, eyes fixed on the multiple screens that made up the strategium's main display wall. The aides working below acted and interacted like organic parts of a complex machine, the hub of which was Captain Stenius in the command throne. Inquiry and reply, report and command all flowed through the ship's captain, who orchestrated the whole endeavour with curt responses and clipped orders.

Corswain could only imagine the thoughts occupying Stenius at the moment. Warp translation was difficult enough in perfect conditions, and the current conditions were far from perfect. Another glance at the Lion showed Corswain that the primarch's attention had moved, from the grey blankness of the screens to Stenius.

It was impossible to discern real meaning from the primarch's inscrutable glare, but that did not stop Corswain from speculating, occupying his mind with such idle thoughts in order to distract himself from the coming moment when reality and unreality would clash and they might all be wiped from existence.

The Lion's comments regarding Stenius concerned Corswain on two levels. At first hand, he wondered what he had missed that had been seen by the primarch's insight. Corswain was, for the moment at least until they were reunited with Luther and the rest of the Legion on Caliban, the right hand of the primarch. It was his duty to foresee his master's commands and act before they required the Lion's attention. If there was some facet of Stenius's manner that he had missed, Corswain felt he was not properly fulfilling his duties.

Contrary to this was the worry that there was nothing amiss in Stenius's behaviour, which did not bode well for the Lion's current state of mind. Since Tsagualsa the primarch had brooded, even more than Corswain had become accustomed to. His master had said nothing of what preoccupied his thoughts, speaking only of the ongoing campaign against the Night Lords, but even those conversations had been touched by a new determination, bordering on a hunger for victory that Corswain had not seen in the Lion since the earliest days of the Crusade. The seneschal's brush with death had forced Corswain to acknowledge his own shortcomings and apply himself to his duties with greater endeavour; perhaps the primarch felt the same.

'Warp translation in ten seconds.'

Stenius's monotone declaration cut through Corswain's meandering thoughts. He balled his hands into fists, knowing what was to come. The Lion stepped forwards, gripping the balcony rail in both hands as he stared down at Stenius, eyes narrowed. The primarch opened his mouth a little, as if he was about to speak. He said nothing and shook his head slightly, lips pursed.

'Beginning translation to real space.'

This was the part Corswain hated the most, in sensation most alike to the disembodied lurch of teleportation. For an endless moment the Invincible Reason was held between two dimensions, perched on the precipice between the material and immaterial like a wanderer standing at the crossroads of fate. A moment before, it had been adrift on the tides of the warp, cocooned within a bubble of reality kept intact by its Geller field. Now it was in the true universe, plucked from the unnatural currents, its Geller-borne reality imploding as real space engulfed the vessel.

Corswain's head reeled for several seconds, dizzied by a sense of unreality, his surroundings seeming out of step with him, disjointed and fragile.

The sensation passed, leaving a faint pulsing behind Corswain's eyes.

The Lion was already barking orders for the short-range scanners to be brought online, eager to see whether his plan had worked and the phantom ship had been dragged out of the warp by the risky manoeuvre.

'All power to local augurs and broad-band auspex sweeps,' said the primarch, striding towards the long sweep of stairs that led down into the main chamber of the strategium. 'Redirect long-range signalling and sensors to comm-net scans. Find me that ship!'

The systems of the Invincible Reason scoured the surrounding space for seven minutes. Corswain and Nemiel had followed their primarch down to the main floor, and had been joined by Captain Stenius who had surrendered his position of direct command to the Lion. Nothing was said for those seven minutes, as the scanner technicians worked feverishly to determine whether the plan had succeeded.