Chapter 115: Don't Tell Me This Is Cawl's Laboratory
The chemical waste that had once been lethal enough to kill tens of thousands of people had become, across several centuries of heat and sedimentation, a dense crystalline solid underfoot. The combined force crunched through it with every step, the sound sharp and carrying in the dead silence.
According to the coordinates Venus was navigating from, they had approximately twelve hours of travel ahead of them through the sewage main before reaching the target point. That was the theoretical calculation. In an underhive of this age and condition, theoretical calculations were aspirational.
The lead element was not long into the main passage when Stroud's recon team transmitted a contact report.
"Boss. Small ambush. Targets show extremely unstable biological signatures. Clearing now." The register of Stroud's voice communicated that whatever he had found did not require any adjustment of his attention.
The tactical display lit in Duvette's peripheral vision, showing a cluster of red contacts at the approach to the next junction. By the time he had registered them, they were already going dark.
When Duvette and Venus reached the contact point, both of them paused.
Twelve bodies, twisted on the crystalline floor. The basic silhouette was human. The specifics were not.
Chests expanded to more than twice the normal cavity volume, the adaptation of creatures that had been breathing thin, contaminated air for generations. Skin a morbid grey-white, hairless. The nose reduced to two small apertures. And the eyes, enormous, forward-set, protruding, covered with a grey keratin film that caught what little light reached this depth, the result of long adaptation to complete darkness.
Venus crouched and turned one of the bodies with the tip of her blade. Her voice was analytical.
"Exterminatus survivors. Populations that reached the deep defensive infrastructure before the virus took effect. Several centuries of isolation in these conditions, with whatever residual radiation the substrate still carries." She stood. "They have moved past the definition of human in any practical sense. What's left is something built for this environment specifically."
Duvette looked at the bodies without particular expression and confirmed the assessment with a nod. As long as these things could not grip a lasgun and aim it at him, they did not constitute a meaningful threat.
"Continue advance. Do not spend time on these."
The reality of the journey exceeded the estimate. The hive's internal structure had absorbed catastrophic damage during the Exterminatus event. Hundreds of meters of load-bearing reinforced plasteel and structural material had come down and filled the original passages, turning the planned route into a series of detours that ate time. Their best cutting equipment made slow work of the material when a detour was impossible. And the feral mutants pressed from the shadows at irregular intervals, each engagement brief and decisive, but the accumulated delays were not.
When they finally reached the destination coordinates, the journey had taken well over twice the projected time.
"This is the location?" Duvette looked at what was in front of him. Collapsed metal, shattered conduit, ash and debris in sufficient quantity to have buried whatever had originally been here under a considerable mass. His brow contracted.
Venus checked and rechecked the coordinate reading inside her mask. "The readings are correct. It is here. Beneath us."
He exhaled slowly through the filtration mask.
"So we dig."
He turned to Anderson. "Get the melta cutters and demolition equipment. Full rotation. I want to see what is under this, whatever it takes."
What followed was not quick. Through the hours of cutting and controlled demolition, the 112th's veterans working in organized shifts, the Mechanicus Explorator directing the demolition geometry with the precise Cant of someone who understood structural collapse patterns, a space opened in the debris, and in the floor of that space, a vertical shaft descended into a darkness that did not reflect any of the lighting they were using.
Stroud threw a luminescent marker rod into the shaft. It fell for a considerable distance before the light reduced to a small point.
The Mechanicus Explorator had been at the shaft rim for some time, running his instruments along the edge.
His vocalizer produced a sound that communicated agitation.
"Auspex signals are severely distorted at the shaft boundary. Scan return: zero. Magnetic shielding class: extreme."
Duvette stared into the dark opening and had a thought he had been having, in various forms, since before they departed Pyrite.
Please not Necrons.
"Let me take my people down first."
Stroud had already confirmed the descent line was adequate and was volunteering to lead the initial drop.
"Hold." Venus's voice cut across. She looked at Duvette. "Your soldiers have done more than enough on this approach, Colonel-Commissar. The initial descent risk is the Carpé family's to share."
He regarded her for a moment and stepped back. He signaled the 112th to establish a defensive perimeter around the shaft.
A squad of Carpé household troops in carapace armour, armed with boarding shields and shotguns, went down the descent line. The shaft's silence absorbed them.
Everyone held position. The interference in the communications channel was severe, producing fragments.
"...safe...proceeding...space...clear..."
Duvette and Venus exchanged a look through their sealed masks. Both nodded.
The main body descended in organized groups, down the line and into the space below. When Duvette's boots met solid alloy, he checked the tactical display immediately.
No red contacts. No marked threats of any kind. Whatever was down here currently had no occupants that the System classified as hostile.
Venus had moved to the nearest wall and was running gloved fingers along its surface. The material was smooth and consistent, carrying a faint silver-grey sheen in the team's illumination.
"The scale of this space." She tilted her head upward. The ceiling was several dozen metres above them, the passage extending in both directions with a width consistent with heavy industrial movement. "Nothing civilian or standard industrial was built to these specifications. Something very large was intended to operate here."
The Mechanicus Explorator was pressed against the wall with multiple instruments deployed, producing Binary in a continuous low murmur.
The advance scout squad reported again. The signal was worse than before.
"...ahead...large...chamber...you should...see this..."
They moved.
The passage carried them forward in the red-light silence until, without any warning that the facility's power systems gave them, the overhead illumination activated.
White light flooded the passage from ceiling apertures.
"Cover! Everyone down!"
Both Duvette and Venus had the same order at the same moment. The 112th was already moving, pressing to walls, weapons forward.
Duvette braced against the wall and waited. His memory produced, with unhelpful specificity, the laser cutting arrays aboard the Eternal Lament, and the particular experience of being the thing those arrays were directed at.
The lights shifted from white to red.
An alarm engaged along the full length of the passage, the sound sustained and penetrating. From ahead, somewhere in the structure that the red light hadn't fully reached, a sound arrived: heavy, rhythmic, the percussion of something with significant mass moving under mechanical motivation.
Two shapes emerged from the far end of the passage.
The lascannon discharge that preceded them was not a warning. It hit the forward elements of the Carpé household troops at full combat output. The carapace armour, which had been high-grade equipment, performed its function as well as high-grade armour could against direct heavy laser fire, which was not well enough. Several soldiers went down and did not move.
The shapes continued forward.
Duvette processed the silhouette: rounded armour panels. Chest-mounted heavy weapons. Enormous power fist assemblies at both arms. The distinctive spherical head construction.
Beside him, the Mechanicus Explorator produced a sound in Binary that did not require translation for its emotional content. The word "Omnissiah" was legible even through the artificial vocal register.
The threat display in Duvette's vision was showing two large deep-red contacts with the particular intensity that indicated something operating well outside standard threat parameters.
"Anderson! Heavy weapons, plasma and melta, concentrated fire! All of it, now!"
The 112th's heavy weapons teams had deployed the moment the contacts appeared. Plasma discharge and melta beams converged on both targets simultaneously from multiple angles.
The robots had a defensive field active. Under saturation fire from a heavy weapons element that had been calibrated against Tyranids for months, the fields had a finite operational period. Metal fractured. Something in the internal power systems reached its critical threshold.
Both constructs came apart in the particular manner of things that contain significant stored energy at the moment they lose structural integrity.
Duvette walked through the dissipating smoke toward the wreckage.
The rounded armour plating. The massive power fist housings. The spherical head assembly, now in fragments but still identifiable from the profile.
He stopped.
"These are Kastellan Robots." He said it to himself as much as to anyone in range. "Why are Kastellan Robots in the underhive of an uninhabited dead-world system? Dark Mechanicus?"
The Mechanicus Explorator had gone directly to the wreckage and was working through the debris with frantic attention, searching for anything salvageable from the logic engine components.
Anderson's team had been thorough. The Explorator straightened and emitted a burst of Binary that communicated his assessment of this fact without any ambiguity. The content was approximately: nothing useful remained intact.
The advance squad reported. This time the soldier's voice carried something beyond the communication interference.
"My Lord. Sir. There is a large arched chamber ahead." A pause. "You need to come and see this."
Duvette and Venus moved forward at pace.
The chamber was vast. Under the emergency red light, several hundred armed servitors stood in dense rows across the floor space, their weapon mounts visible even through the accumulated evidence of extreme age. Interspersed among them, the distinctive profiles of Kastellan Robots, dormant, but projecting an ambient weight of presence that distance did nothing to diminish.
The servitors were largely beyond recovery. Millennia without active maintenance had done to their organic components what time does to everything organic, and the stasis fields that had been running here had failed long before whatever trigger had woken the two patrol units above. Most of the armed servitors had resolved into oxidized components that maintained only the posture of what they had been.
The Kastellans had held.
The Explorator moved through the chamber with the manner of someone who has arrived somewhere they were not prepared to arrive. The Binary coming from his vocalizer was continuous and had shifted registers entirely, not distress, but something closer to the response of a person who has encountered something they cannot immediately categorize.
"These models." The words came out in comprehensible Gothic as if the concept required a language the Explorator trusted more. "These configurations. These are relics of the Great Crusade era. Ten thousand years old."
Ten thousand years. Great Crusade era. A hidden installation with no official records, on a dead world in a peripheral system that nothing of importance had any reason to visit. Armed with ancient war constructs that had been guarding an empty facility for ten millennia.
Duvette's gaze moved past the dormant rows to the door at the far end of the chamber. The passage beyond it led deeper.
He stared at it.
A thought arrived that was, on its face, completely unreasonable. The evidence in front of him assembled it anyway.
"Emperor's mercy," he said quietly. "Don't tell me this is one of Cawl's laboratories."