Paul was a fast walker.

  She could not tell if it was because she was still shaken or because he had some augmetics she could detect, but he seemed to move faster than his gait would suggest, almost gliding over the shadowy path like a mirage. Always just slightly farther than expected.

  “Paul?”

  “My lady?”

  “Did you serve in the Imperial Guard before you were assigned here?”

  “Ah.” He gestured at his clothing. “I can see why you would think that. But alas, it is just decorative. My lord-father, doting as he was, pulled some strings with the Munitorum to purchase a high-ranking commission for me. He thought that if I was promised to the Militarum, his agreement with the mech-lords of my planet would not hold any more.”

  “It did not work.”

  “It did not work. But I kept the commission. The Munitorum has me listed as an OSD, officer on special duty. Mechanicus liaison. Indefinite deputation. Nice salary, too.”

  “You get your salaries paid out here?”

  “Not in hand. But the payslips are as good a medium of exchange as banknotes out here.”

  “Interesting.” She crossed her arms. “So… Are you going to tell us something about why we are walking in a forest of entombed Aeldari?”

  Paul bowed his head slightly. “My apologies, but I am not quite familiar with the science behind it all. I would much rather let the Arch-Genetor explain. Speaking of which…”

  Galiel had heard that the trope of a witch living in a forest house was very common in literature. She had always found the idea rather absurd: if everyone knew there was a witch in the forest living in an identifiable dwelling, why had Imperial authorities not executed her yet? However, at the sight that now greeted her eyes, she could dimly appreciate the mental image an author conjured to suspend disbelief in the concept.

  In a small clearing before them, a ramshackle pre-fabricated unit rose up to two uneven stories in height, constructed in a haphazard alignment that was structurally unsound to a frankly astounding degree. In fact, it was clear to her eyes that the only reason it had not collapsed into a neat pile of plascrete yet was the ad-hoc structural support it was receiving from its symbiotic partner: a massive, milky-white tree, with translucent branches that coiled and intertwined seamlessly with the fabricated components. The whole arrangement had the appearance of a treehouse some child had built on a young tree, which had then been splintered and forced apart as the tree grew up and through it. Growing and whispering here and there were thickets of the same stalactite-like leaves she had had the misfortune of seeing up-close what felt like mere seconds ago, though her chrono-metric tools told her that tens of minutes in ship time had already passed in transit. The tree looked overall like a more mature, organic version of the regular denizens of the White Forest.

  “Arch-Genetor Xani’s lab,” Paul whispered. “It is built around the first White Tree, the oldest of the specimens and the only functional producer so far. She is inside.”

  Unlike a lot of the Biologis architecture so far, the Arch-Genetor’s Laboratorium used traditionally mechanical moving pieces. If anything, they were perhaps a little too anachronistic: Theta had to open the door with a manual hand crank to let them proceed inside. At least the decontamination shower waiting on the other side was refreshingly familiar.

  So was the hodge-podge mess, featuring tables overflowing with clicking contraptions, cages and boxes covered with heavy cloth, large vats of biotic medium with organic samples, and stuttering machinery running half-finished code. It was a sight she and many other junior Adepts knew all too well: the playground of a Magi who had allowed themselves the conceit of playing at invention, rather than following their sacred calling of rediscovering the Omnissiah’s wisdom. For an adept, doing so would be rewarded with electro-lashes at minimum. A Magos with the same beliefs was merely tutted at, like a mischievous child. Just another one of the Mechanicus’ many inequalities she had come to understand over the years: as in all things, Knowledge and Experience was Power.

  What was strange, however, was how strangely old and outdated the Laboratorium seemed. The cutting-edge Data-Light prisms of Exelion-IV, high-bandwidth Noospheric tethers, gossamer-like threads of the latest in Manifold access technology—all things she had come to expect as standard aboard the Ark Mechanicum—were completely absent here. But that was to be expected: after all, the research was sensitive to energy.

  What was unexpected was the clearly outdated equipment setup for experimentation. There were no Machine Spirit terminals, diagnostic augury tables, or industrial-grade datacubes. Instead, spools of magnetic tape lazily ran between lazily spinning recorder-writer cylinders. Ancient transistors and vacuum tubes hummed and sparked to feed motive intelligence through an ancient pixelated monstrosity of a display terminal; the setup barely seemed robust enough to run the quaint games she used to play on data-slates as a child, let alone hosting the inquisitive djinns of research suites. A few heavily shielded particle microscope arrays, sterilization chambers, and gene-mod tools were stashed away in the corners. A mounted system of pullies, gantries, and sturdy ropes on the ceiling connected to a number of trapdoors and elevators on the floor, seemingly leading to some sort of storage space in the basement. And, of course, the central spot of honour was taken up by the White Tree. Its main trunk rose up through the centre of the Laboratorium and out the ceiling through a neatly made gap in the machinery. The white gem-like body was festooned with wires and sensors, connected to silent machines that she recognized as Astronet relays.

  “Where is she?” Galiel whispered to Paul.

  “You are late.”

  The distinctively organic female voice bounced down to her auditory ports from somewhere up in the ceiling. It did not bear any of the tell-tale artefacts of synthesized flesh-voice. No, it had come from a real set of vocal chords.

  “Arch-Genetor?” she questioned hesitantly.

  “In a moment, darling. Something is gumming up this elevator. Is someone down there? Give the girl a top-up on the immunity serum. I haven’t had the time to report back to the main Temple on the psyber-ecosystem growth rates. It’s accelerating! Changing! Evolving!” The voice almost giggled. “How wonderful! It’ll kill you dead if you let it, but it’s so wonderful!”

  “There is no one down here, my lady!” Paul called back. “All the Adepts and menials have left on their assigned rotas.”

  “What? Didn’t I schedule one or two on lab duty?”

  He fiddled with a small vellum cylinder before answering. “That was last week, Arch-Genetor! No Adept has been on lab duty since then!”

  “Blast it! So much to do, so much to do! Well, you know how to do it, don’t you, Paul? It is Paul I’m speaking to, right? I can’t tell you aristocrats apart!”

  This was followed by the characteristic loud clang of something important slipping from one’s grip, and then an immensely loud whining and tearing sound. A few moments later, one of the carbon-fibre ropes attached to the ceiling broke free and crashed to the ground, obliterating a spool of magnetic tape.

  “Rats.”

  Paul carefully tiptoed around the wreckage and picked up a vial and a diffuser from the table. “Yes, Arch-Genetor. This is Paul.”

  “Well, Paul, can you throw me the plasma cutter again? It’s still on, so be careful! I don’t want blood and gore on my machines!”

  “Magos, perhaps you can deal with the gantries after this order of business? The clock is ticking on the whole spinehugger situation.” Val lifted the heavy rope with a finger and extracted a slightly crushed knot of tape from under it.

  A lithe figure leapt from one of the rails, landing lightly and silently in one of the shadowy corners. “Spinehuggers! Hah! I read that name in the meeting minutes. Pretty damn creative.”

  Paul brought the loaded diffuser and sprayed down all four of them. The virion suspension was as bland and odourless as she remembered. “There.”

  Arch-Genetor Xani sauntered into the light, pausing to toss a toolbox onto the nearest messy table. She looked completely unaugmented to the eye: a tallish, dark-haired woman with bright brown eyes, dressed in grimy work pants and a dusty black sleeveless vest. “One of the shimmer-lichen colonies got in through the ventilation again. It’s growing on the pulleys. We’ll need more hands to scrape it off anyway.”

  Galiel sank to one knee and lowered her head, silently hoping the others would follow her lead. “Arch-Genetor, it is an honour. I am Enginseer Galiel Tunakha, here on orders from—”

  “Yes, yes, Aldren sent you, I know. I missed another one of his blasted meetings, didn’t I?”

  Theta slammed a fist to his chest in a traditional Skitarius salute. “My lady, it is an honour to meet you. My commanding officer, when I was a neophyte, told me he served under you. He had nothing but praise. Mu-167. He was a part of your own Ixizan-12 batch.”

  “Ah, Mu! How is he nowadays? We got up to a lot of shenanigans together. I made him climb up a Krootox’s anal tract once. Fun times.”

  “He was slain during the Tyranid invasion on Sanctus Ferrum, blessed one. He fell fighting the Swarmlord with Archmagos Xavik.”

  “Oh.” Arch-Genetor Xani scratched her head. “My condolences.”

  “It is a Skitarius’ greatest honour to die in the Machine God’s service. He died proud.”

  “Excuse me, little girl, can you fetch the Arch-Genetor from up there?” Rogal waved at her. “We are very busy.”

  Galiel whipped her head around in shock, but then she realized that they had subconsciously switched to binharic cant ever since the Arch-Genetor had descended. He had no idea who she was. Even more surprisingly, her organic vocal apparatus seemed perfectly capable of canting the Lingua Technis.

  “Adsecularis,” Theta snarled, “This is Arch-Genetor Xani. Show her the appropriate respect, or I shall flog you where you stand!”

  Rogal blinked at her. “This… You… You are a priest, my lady? Forgive me, perhaps the long hours on the work floors have blinded me. I could swear you had not a hint of metal on your body.”

  You might be reading a stolen copy. Visit Royal Road for the authentic version.

  Arch-Genetor Xani tilted her head. “This is a curious one. Where did you drag him in from?”

  She hurried to her feet, switching back to Low Gothic flesh-voice. “This is Rogal, my lady. A menial from the Purgatus quarters. He is assisting us with the more… informal parts of the investigation. Or at least he is supposed to.” She shot him another glare. “So far, he only seems to be good for disrespecting his betters. I can discipline him immediately if you wish.”

  Xani waved her hand. “Leave him. I don’t have time for all these politics. Yes, I’m a Techpriest, Rogal, though I’m sure you’ve not seen my kind before. And you’re right. I don’t have any visible metal on my body. That’s because I am an Organicist. I work with the biological sciences and believe in the purity of the human form. That’s all I have time to explain. Now come with me. You will talk while I work.”

  She headed over to an extremely low-resolution terminal and turned a crank on its side. The machinery turned one of the closer magnetic readers, spooling the tape through its head. The screen slowly came to life, revealing a slowly rotating three-dimensional image of the White Tree. Xani rummaged around in her pockets before producing some kind of card with holes punched into it, which she proceeded to insert into a slot in the machine. Immediately, lines of primitive code appeared in black boxes around the diagram. Galiel tried to read it, but her knowledge of this programming architecture was rusty at best. She could only make out some hints of bio-analytics and libraries for processing output from psychic sensors.

  “Interesting… psychic throughput looks good on the overall, but the Leitzmann wave patterns, hmm… And there is a dead zone near Branch 22. Why? Did we get parasites again? Let’s try the Xefover Antibody this time, then… But the catalytic potential… Maybe the Fedzburgur chimeric antigen could be… No, that wouldn’t work.” She looked over at Galiel. “Any ideas?”

  Her oculars snapped shut and open. If she could blink, it would look like an animal caught in front of a Goliath truck. “Um…”

  “Yes, of course! The Umber process! Thank you!” She skipped away from the terminal, swiping a large scalpel from the table. “Come on! No time to waste.”

  She dragged them over to the tree trunk and began palpitating the side, apparently trying to feel for any softness. “Here? No… Here! Touch that!”

  Galiel laid her hand on the place she was pointing at. It felt oddly cool and smooth to the touch, but there was nothing off that she could place.

  “Feel it? Push a little harder!”

  She complied, applying a little pressure. Immediately, she saw the problem. The apparently hard surface had the slightest bit of give. The area underneath felt soft and rubbery. If she were working with living tissue, she might have diagnosed it as a cyst or an abscess.

  Xani saw her expression and nodded. “That’s a dead zone. The material formation hasn’t been viable under there, possibly due to improper matrix crystallization. Without the right framework, the psychic energy goes everywhere. Gets malformed. We need to extract the diseased tissue and debride the matrix. Keep applying pressure there to compress the part, I’ll go in from the side.”

  She pressed a small button on the handle. The scalpel buzzed with the telltale hum of a psi-disruption field. Galiel kept her hand firmly on the indicated point as the Arch-Genetor made a small incision next to her thumb, slowly working the gap open as she reached deeper. Approximately two seconds in, the mass wriggled under her palm, prompting Xani to make a series of swift twists and cuts and then withdraw before she had time to process the motions.

  “You can let go now, girl.”

  An entire chunk of bark came away as she lifted her hand off. The inside was luminous and geode-like, except for the large grey tumorous growth in the centre. Xani carefully worked the scalpel around its back, cutting in neat concentric circles until it came off. Galiel gingerly caught the lump as it fell. It was like a rubber balloon to the touch, filled with some sort of fluid she did not want to identify. Despite an insistent voice in the back of her mind that urged her to get back on topic, her curiosity was far stronger.

  “Arch-Genetor, forgive me… but what is this?”

  “What does it look like?” she shrugged. “It’s diseased Wraithbone.”

  Wraithbone. Of course.

  She kicked herself for not noticing sooner. The texture. The psychic equipment. The sensitivity to energy.

  “You’re… growing Wraithbone?”

  “Indeed. This is the only viable producer so far, but we’ll have an Arborium of these soon enough. Mark my words.”

  She looked back at Val, who had been observing their operation with great interest. He merely shrugged. “Makes sense.”

  “How does it make sense!?”

  “But… How? My lady, Wraithbone can only be grown and shaped by—”

  “The Aeldari, yes. Well, you are only half-right.” Using the scalpel, Xani scraped off some of the healthy Wraithbone under the dead zone. “Any advanced and properly trained psyker can shape Wraithbone. I have read rumours in the ancient Martian lexicons that the Omnissiah himself was capable of Bonesinging. But the secret of singing Wraithbone out of the Warp—the creation of the seed material itself—was out of our reach. No Xeno, even on pain of death or torture, would reveal the art.”

  Galiel nodded. The Xenologis even theorized that it was more instinctual than conscious: the same way birds made nests, Bonesinging training unlocked some instinctual memory that allowed the Aeldari to manifest Wraithbone.

  Xani pulled out a glass vial from her belt and emptied the contents over the hole in the tree. The chemical sizzled and coagulated, forming a black tar-like substance. The smell almost threatened to knock her to the ground. “Well, this was only true until a few decades prior. The Magi of Sanctus Ferrum received word that some Chaos-aligned forces had begun experiments with singing Wraithbone out of the Warp. I’m sure I don’t need to tell you why that would be disastrous.”

  “Arch-Genetor, perhaps this information should not be thrown around in an unclassified space,” Paul warned, glancing mostly at Rogal.

  “Oh, leave him. It will soon be public knowledge anyway. As I was saying, girl, Archmagos Aldren was personally dispatched to bring these traitors to heel, but his true mission was different: secure the means and materials of their research. The techniques he found there, albeit primitive and doomed to failure, form the base of what we have done here now.”

  “Using knowledge gained from the Archenemy? Arch-Genetor, even my knowledge is ignorance before yours, but…” Galiel hesitated. There was no way she could phrase this without being confrontational. “Are you sure this is wise?”

  Xani gave her a smile and emptied another vial of orange fluid over the hole. Galiel itched to perform a spectrographic analysis of the chemicals, but instructions had been clear: no auguries.

  “Don’t worry. There is no arcana or any of Hekaton’s pseudo-scientific nonsense involved here. Just plain and simple science. Come here.”

  She grabbed her arm and dragged her over to a corner of the room, pressing a button on the wall. The nearest elevator immediately groaned and trundled to life, raising a cage from the basement. Xani removed the cloth covering it, allowing her to gaze upon the prone and naked form of an Aeldari. The Xeno was emaciated, eyes squinting at the sudden light. He moaned, trying to crawl into the opposite corner of the cage to get away from them.

  “This is one of our captured Aeldari Bonesingers. Do not fret, he is harmless, though we have to starve, sedate, and occasionally beat him to keep him off-balance. A regrettable damage to the specimen, but there is little choice. There are thirty more like him below us, with hundreds more in cryogenic storage in the ship’s bowels.”

  She motioned to Paul, who grabbed an electro-prod and shocked the Xeno. He let out a strangled scream as his back arched, falling again. Xani used this opportunity to push her hand through the bars and grab his neck. Her hand flowed and shifted, turning into a thicket of tentacles that held him fast against the metal as she leaned and whispered something into his ear. Galiel detected the metallic tang of hallucinogenic infrasonics even from a distance. He moaned and twitched, eyes fluttering. After a few seconds, she let him go.

  “Doing this manually is a pain, but the adepts have left with the equipment to work on the specimens already planted. We are using the cognitive techniques developed from the False World project in the Spire to control these Bonesingers. Basically, we make them undergo severe torture and trauma to trigger a psychological dissociative response, and then utilize auditory, visual, and pharmacological cues to trigger maladaptive reality formation. The end goal is to place them in a form of false reality that evokes their instinctual Bonesinging responses. The initial experiments were harrowing. We lost nine out of ten subjects to suicide or shock. But with the improvements to the process, we are now at a sixty per cent success rate.”

  “Pushing seventy now, my lady.” Paul was injecting a syringe into the catatonic specimen’s neck. “With the new drug formulations.”

  “Wonderful! Either way, as you can see…” She pointed at the Bonesinger’s trembling hands, which were sprouting small, translucent shards of Wraithbone. “This specimen is already close to viability. Once we achieve a stable and continuous output, we will do a planting procedure. The substrate outside has been specially crafted and charged with chemicals and psychic detritus that encourage proper Wraithbone formation. Once the specimen is properly secured and connected, he will be given further suggestions and drugs that encourage the Wraithbone to form in an easily harvestable format. This is far off in the future, but we are even looking into cross-breeding some of the specimens and creating stable lineages of producers! Imagine how effective our psychological regimen could be if started early in life!”

  “The last time I was here, you were using some sort of stones.” Val crossed his arms. “I assume they were soulstones.”

  “Indeed, we were using soulstones smuggled out of Craftworld infinity circuits at the beginning of the programme. But it was quickly becoming non-viable. The Aeldari fight like demons to guard their soulstones. But one or two hundred lost Bonsingers? Even for a dying race, that hardly makes a dent. They are often less well-defended, and thus easier to procure. My project requires a stable population of the Xenos. I shall not be unsustainable.” Xani skipped back to the table and picked up a large chunk of Wraithbone. “Once I perfect this, there will be stable Wraithbone production facilities on Sanctus Ferrum. We will be able to match the Aeldari supply chains in combat! The possibilities are endless, especially in combination with the Astronet programme! Can you imagine? Every Techpriest, every Skitarius, with his own psychically mouldable Wraithbone complement!”

  “Camps could come up and go down in minutes, blessed one,” Theta rumbled, “Weapons adapting on the fly. Alteration of augmetic loadouts in seconds. Better guns. Better armour. Better vehicles. Better outcomes.”

  “Yes, Theta-4-0, yes! Better everything! And we could even export it to the other Forge Worlds, if the Archmagi sanction it!” Xani handed Galiel the Wraithbone. “This single technology, once perfected, will revolutionize Imperial military power.”

  “Praise the Omnissiah,” Rogal mumbled, his eyes wide as he stared at the chunk in her hands. “There is such technology in this world?”

  “The Omnissiah’s miracles are endless,” Galiel answered, only half-aware as her eyes darted between the Wraithbone and the delirious Bonesinger in the cage. She could feel the power coursing through her hands already, thrumming in her Astronet nodes. Hesitating, she reached out and touched it with her mind. Immediately, the material responded, rippling as it reconfigured itself into her chosen shape: a knife.

  “You can Bonesing!” Xani exclaimed.

  “Rudimentarily, my lady. I have studied some of the confiscated manuals. But this is Xenotech. Forgive me, Arch-Genetor, but will the priesthood ever stand for this? And even if they do, the method of production… The Aeldari are Xenos, but they are sentient. This seems… inhuman. Unethical. We do not work on the consciousness. Not like this.”

  She regretted her words as soon as they came spilling out of her mouth. Xani gave her a thin-lipped smile and gently took the dagger from her hands. “Archmagos Aldren has sent you here for a solution to the spinehuggers, correct?”

  “Yes, Arch-Genetor.” Val interceded before she could dig her grave deeper. “Do you have any ideas?”

  “I have a few, but I am not sure if they will satisfy Enginseer Tunakha’s moral principles.” She tossed the dagger onto the table.

  “Arch-Genetor, I meant no disrespect,” Galiel stuttered despite herself. Shit. She absolutely could not stutter. She had to be definite. Rational. “The research is overwhelming in its sophistication.”

  Xani raised a hand. “I understand your trepidation, but the first iterations are always messy. Inefficient. If we can discover a more humane, resource-efficient method, believe me, no one will be happier than I am. But for now, this is what I have. And you will need it for your work.”

  “Need this, my lady?”

  “Wraithbone is psychically attuned. I have studied the documentation we have on the spinehuggers. Their potential for material pluripotency seems to be near-infinite, but psychic signatures are much harder to mask. The records of Inquisitor Ravenor had the description of a sort of Wraithbone-based tracking device. I had the opportunity to study it during a brief sojourn in the Inquisitorial Fortress on Terra. If I can replicate the design, link it to your Astronet systems…”

  “We might be able to track the spinehuggers regardless of what form they take.” Galiel blinked. “That is an elegant solution, Arch-Genetor. Thank you.”

  She waved her hand. “The Wraithbone for this purpose will need to be purpose-built and sung. You will have to help me.”

  She bowed. “If it is within my competence, my lady.”

  Galiel was already on thin ice. She knew better than to anger a ranking Magi on a ship far from Imperial civilization. She definitely knew better than to do it twice.

  Xani pointed at Val and Theta. “You two, go with Paul. Find at least two of my Adepts and bring them back to the Laboratorium. This overrides their rotas. And as for you…” She looked at Rogal. “…Don’t touch anything."