The stairwell down to refinery control felt like the throat of something dead.

  Metal steps ran in tight switchbacks, slick with tracked-in water and grime. Emergency strips along the walls threw out a dull red glow, just enough to keep shadows from swallowing everything. The storm's roar faded behind them with each level, replaced by a deeper, more constant vibration that Vega felt through her boots and in her teeth.

  Machinery, still running somewhere below.

  "Level markers are out," Ito said quietly, scanning as they descended. "We passed where Sublevel One should be ten meters ago. Somebody rewrote the building without telling the signs."

  "Keep counting by the steps," Vega said. "Our maps are already wrong. I want at least our own marks."

  Park went first, rifle up, moving with deliberate care. Her armor's joints whispered every time she shifted weight. Behind Vega, Watson and the rest of Bravo came down in a staggered file, weapon muzzles tracking the spaces between pipes and platforms.

  Half a landing later, Vega stopped.

  A dark, viscous smear stained the wall ahead, thick and uneven, with a metallic scent that made her stomach tighten.

  "Contact," she said. "Mark it."

  Ito flicked his wrist. A tiny beacon snapped from his gauntlet, stuck to the wall, and pulsed soft blue on their shared map.

  "Somebody came this way," Vega said. "Not all that long ago."

  The smear was still tacky along one edge where moisture had streaked it, a thin line leading down the next flight of stairs.

  "Still no bodies," Watson muttered.

  "Do you want one?" Park asked without turning.

  "No," he said quickly. "Just… you know. Missing pieces."

  Vega kept moving.

  The deeper they went, the more the vibration changed. It stopped feeling like simple machinery and took on a slower, pulsing rhythm, like the throb of a distant, heavy heart.

  Her HUD flickered once.

  "Signal loss?" she asked.

  "Interference," Ito said. "Electromagnetic noise is climbing. Could be local generators overloading. Could be something else. Our link back to the surface is already degraded. I am getting occasional packet drops from Taggart's channel."

  "Enough for voice?" Vega asked.

  "For now, yes," he said. "Data might be another story."

  "Keep me posted," she said.

  The stairs ended without warning.

  One moment, they were spiraling down; the next, the steps stopped at a wide landing fronted by a blast door that had been forced open. The thick slabs of composite and steel were twisted, edges scorched. Something had hit them from the inside with tremendous force.

  Beyond, refinery control waited.

  The main control room was a circular cavern carved into the rock and lined with consoles. Holographic displays flickered in wounded loops above dead operator stations. A ring of tall server towers enclosed the central pit like standing stones.

  The first thing Vega noticed was the smell.

  It was worse here, heavier. Burned insulation. Hot metal. Under that, something organic, sweet, and rotten at the same time, like meat left too long in a sealed space.

  The second thing was the sound.

  The pulse in the air grew stronger, interference rising until it felt like the room itself was under pressure.

  "Helmets stay sealed," she said. "I do not care how tempting it is to puke. You do it later."

  "Noted," Watson said faintly.

  "Park, sweep left with Alpha. Watson, right with Bravo. No one goes into the central pit until Ito and I clear the stations."

  They moved.

  Broken chairs and scattered tablets crunched under their boots. Some consoles were dark, screens cracked, and dead. Others still glowed weakly, error codes scrolling along the surfaces like silent screams.

  Bodies lay here too, but fewer than Vega had expected.

  The story has been stolen; if detected on Amazon, report the violation.

  One technician slumped across his station, face almost entirely eaten away by whatever had burned him from the inside. Another lay on the floor near the far wall, chest cratered by the same clustered punctures she had seen upstairs.

  Ito went to the nearest active console and tapped the manual override.

  The display resisted for a second, then flared brighter, sharp lines of code and schematics ghosting across his visor. He muttered under his breath as he navigated.

  "Talk to me," Vega said.

  "Atmospheric controls are offline," he said. "Power routing is chaotic. Something is drawing an enormous amount of juice from the lower grids. It is not labeled as part of the original refinery architecture."

  "Let me guess," Vega said. "Below."

  "Below," he agreed. "Sublevels that do not exist on the standard colony blueprints."

  He brought up a structural diagram. The image shuddered, glitched, then stabilized: a cutaway of the refinery tower and surrounding rock. Habitats above, processing levels here, and then—

  A dark, irregular mass beneath the foundations pulsed faintly.

  "What is that?" Watson asked softly.

  "Not in the schematics," Ito said. "Whatever it is, the system thinks it is part of itself now. It is wrapped around the main power spine."

  "The miners did not dig that," Vega said.

  "No," Ito said. "But somebody probably opened the door for it."

  Park's voice came over the squad channel. "Captain," she said, "you should see this."

  Vega left Ito at the console and stepped through the maze of stations toward Park's position at the far side of the room.

  Park stood near one of the tall server towers, rifle lowered slightly. At her feet lay a body in a torn security uniform. The man's sidearm was still holstered. His hands were empty.

  His eyes were open.

  Vega crouched.

  "Shot?" she asked.

  Park shook her head. "No bullet wounds. No punctures. No burns. He looks… scared."

  The man's mouth was frozen half open, as if in the middle of a word he had never finished. His fingers were curled into his palms hard enough that the nails had broken the skin. Sweat streaks had dried on his forehead and cheeks.

  Vega checked her display. "No obvious toxins in the air," she said. "No immediate pathogens flagged above what we saw upstairs."

  "Look at this," Park said.

  She tilted the body slightly, revealing the back of the man's neck.

  Something had etched patterns into his skin.

  At first, Vega thought they were burns, but the lines were too precise. They crisscrossed his neck and the base of his skull in a complex lattice, like thin, raised circuitry. At several points, the pattern disappeared under the hairline.

  "Implants?" Vega asked.

  "Not Fleet issue," Park said.

  Ito joined them, stepping carefully around the dead man's outstretched arm. He scanned the markings, then hissed softly.

  "That is not standard augmentation," he said. "There is organic signal residue around the etchings. Whatever this was, it was talking to something, and that something was not just metal."

  Vega straightened.

  "Taggart," she said, opening the channel back to the surface. Static bit at the edges of her words. "We are in refinery control. Multiple civilian and security casualties. We have visual confirmation of unauthorized biotech interfaces on at least one body."

  "…say again," Taggart's voice came, distorted. "You are cutting…"

  "Interfaces," Vega repeated, raising her voice. "Something was plugged into these people's nervous systems. It is not Fleet. It is not in the colony charter."

  "Biosafety…" Taggart's reply dissolved into a wash of noise. "…pull out. Do not… repeat, do not…"

  The line went dead.

  Vega waited a beat, then two.

  "Ito?" she asked.

  "Signal is gone," he said. "Storm interference just spiked. We are blind to the surface."

  "Can you get it back?"

  "Maybe, later," he said. "Right now, the entire band is just filled with garbage. It is like something down here is jamming us on instinct."

  Vega looked around the control room, at the dead, at the flickering consoles, at the humming towers, and at the pulsing deep below.

  DO NOT GO BELOW, the wall upstairs had said.

  She breathed once, slow, feeling her armor expand and contract around her ribs.

  "We have enough to confirm this was not an accident," she said. "Somebody modified this place. Whatever they were doing, it got into their systems and their people. Taggart tried to tell us to pull back, but we cannot even confirm he heard us clearly."

  "And Admiral Szeto?" Park asked.

  "If we cannot talk to Taggart, we are not talking to Zheng He either," Vega said. "As far as they know, we are somewhere under a storm with a carrier load of unknowns."

  "Captain," Ito said carefully, "we can get out of here now, bring what we know back to the pad, and let orbit decide what to do with this hole."

  "Can we?" Vega asked. "You said something is on the power spine. Wrapped around it. Drawing from it. If it keeps growing, how long before it reaches the habitats? Or the terraforming plants? How long before it finds another way out?"

  Ito did not answer.

  "Admiral Szeto did not wake us to tag a problem and run," Vega said. "She woke us to stop whatever is happening before it spreads. That means we find the root."

  "Below," Park said.

  "Below," Vega agreed. "We follow the power spine down as far as we can, we get eyes on whatever is drawing all that current, and we find a way to cut it loose. Once we have that, we fight our way back up and tell Szeto what she is really dealing with."

  Watson shifted his weight. "And if there is no way to cut it loose?" he asked. "What if it is already too big?"

  "Then we find where to drop the biggest bomb we have access to," Vega said. "We are not leaving a live infection tied into this grid."

  Park nodded once, slowly.

  "If we go down, we might not come back up," she said.

  "If we do not go down, nobody might," Vega said.

  The thrum in the air seemed to answer, deep and patient and hungry.

  "Park," Vega went on, "leave a beacon here. Full recording. If Taggart or anyone else pushes through the noise, I want them to know exactly what we found and where we went."

  Park unclipped a palm-sized device from her belt, primed it with a thumbprint, and set it on the nearest intact console. It blinked green, then blue, then settled to a steady pulse.

  Ito pulled up the structural diagram again.

  "Sublevel access," he said. "There are service elevators, but they look dead or worse. Emergency ladders in the maintenance shafts here, here, and here. The main conduit runs along this axis." He highlighted a thick vertical line. "If we follow that, we will stay near whatever this growth is."

  "Closest shaft?" Vega asked.

  Ito pointed. "Northeast quadrant. Through maintenance corridor three."

  "Then that is our road," Vega said. "Form up. We are going to see what everyone else was running from."

  She took one last look around the refinery control as they filed out.

  The dead technician slumped over his console. The security man on the floor, strange circuitry burned into his neck. The words upstairs, written in someone's last moments with whatever they had at hand.

  DO NOT GO BELOW.

  She turned her back on them and followed her squad into the maintenance guts of Nemea Nine, toward the deep pulse under their feet.