Detonation of the Barrier

How many tons of hydraulic pressure could the maintenance hatch hold before the beast crushed them against the intake manifold? Dario Melgarejo jammed his heel against the bottom flange of the service gate, gripping the titanium de-icing lance with two hands while the corrugated partition shivered. Five paces ahead, the gateway pedestal flickered under an emergency strobe, its amber screen displaying the master override keycard locked inside an automated quarantine sleeve. To seal Sector C-Fourteen and keep the rising heat from poisoning the lower vaults, he needed that keycard in his fingers before the entire bulkhead warped.

The corrugated steel tore with the screech of peeling lead.

A snout five feet wide punched through the split seam. Black horn-plates, ridged like volcanic basalt, shielded the skull from snout to crest. Thick yellow rime clung to the seams between its armored plates, steaming in the thinning chill. The beast—a Pleistocene short-faced bear swollen with chimeric marrow—snapped jaws lined with triple rows of serrated bone. It slammed its bulk forward again, tearing a twelve-foot gap through the steel framing. Concrete chunks rained from the ceiling, pulverizing an auxiliary tool cart.

"Back!" Soledad Ravelo barked.

She stood braced against the granite door jamb, her pneumatic carbine slung across her chest. In her gloved right hand she held an orange hexagonal brick: a demolition block of pressurized thermite-gel, marked with the red crest of the Guardia Polar. Her left fingers shook with the erratic tremor of radiation poisoning, but she snapped the mechanical arming toggle flat against the casing with a sharp click.

"The cranial armor deflects tungsten darts," Soledad said, her voice flat and raspy through the rebreather. "The charge goes under the thoracic plate, or we feed it."

Behind the compressor housing, Geraldo Sotomayor cowered on his knees, clutching the shredded skirts of his Siberian parka while goose down drifted around his ears. "A thermal explosive in an airtight gallery? Are you out of your mind, Marshal? You will roast us like dried cod!"

"We will burn if the backblast hits the return duct," Dario shouted.

He lunged past the shuddering compressor, pointing the tip of his lance at the heavy steel damper overhead. The ventilation duct was pulling a heavy suction toward the main gateway arch. If the explosive ignited while the damper stood open, the pressure wave would roll straight down the conduit and cook them inside the crawlway.

Dario leaped onto the concrete inspection block. He slammed the hardened tip of his de-icing lance into the manual override cog of the damper housing, throwing his entire body weight downward. The rusted teeth of the gear screeched. Cold grease flaked off in brittle sheets. With a metallic crack, the heavy damper dropped into place, sealing the rear intake and forcing the gallery's airflow outward toward the gateway arch.

"The chimney draft is set!" Dario yelled, dropping back to the floor grates. "Channel vents forward into the vault!"

The chimeric behemoth tore the remaining steel studs from the concrete. Its massive forepaws, tipped with six-inch translucent claws, struck the stone floor with an impact that vibrated through Dario's shins. The beast lunged forward, jaws gaping wide enough to sever a man at the waist, its milk-white eyes fixed on Soledad's uniform.

Soledad did not retreat an inch.

She waited until the steaming snout was three feet from her chest. With a sharp flick of her wrist, she jammed the primed thermite block directly into the beast's open gullet. In the same motion, she threw herself sideways behind the reinforced corner of the granite archway.

"Down!" she shouted.

Dario tackled Geraldo behind the concrete foundation of the primary compressor.

The detonation was not a sharp crack, but a deafening, concussive roar that sucked the breath straight out of Dario's rebreather. A sheet of blinding crimson fire filled the corridor. The pressure wave hit the sealed damper above them with a ringing clang, vibrating the steel plates until rivets hummed. Through the roaring orange glare, the scent of burning hair, vaporized marrow, and scorched basalt billowed outward. The beast let out a gargling shriek as the thermite-gel consumed its vital organs from within, its armored torso collapsing onto the granite pavers like a demolished chimney.

Thick gray smoke poured through the gateway.

Dario scrambled to his feet, coughing against the hot, sulfurous air that tasted of copper and burning rubber. The heat struck his faceplate like an open furnace door. The frost on his suit began to liquefy, running down the fabric in dirty gray droplets.

"The pedestal," Dario wheezed.

The blast had shattered the glass housing around the central console. Flames licked the edge of the control station, and black resin bubbled from the wiring harness. Inside the scorched recess, the master override keycard—a thick slab of tempered quartz inlaid with gold circuitry—was beginning to soften under the thermal wash. If the socket fused, the sector's manual override would be lost forever.

Dario ran straight into the smoke. Heat scorched the outer lining of his sleeves. He drew the pneumatic sealant gun from his belt, aiming the nozzle at the flaming console. He squeezed the trigger. A broad jet of cold methacrylic resin shot across the pedestal, extinguishing the open flame with a sharp hiss of vapor.

Dropping the gun, Dario thrust his brass scraper into the melted latch. He twisted the tool with both wrists, using the leverage of the handle to pry the quartz keycard from the warping terminal. The hot plastic burned through the palms of his heavy mittens, but the locking pins gave way with a sharp snap.

Dario yanked the keycard free, clutching the smoking slab against his chest.

Behind him, Geraldo staggered out from behind the compressor, wheezing and beating at his singed sleeves. Feathers drifted from his charred parka like burning flakes of gray snow.

"My cuffs," the smuggler groaned, his voice cracking with outrage. "The Siberian down is ruined. Singed right to the lining! The administration will pay for this. I demand an itemized dry-cleaning voucher the moment we reach an airlock."

"Be quiet," Soledad said, stepping through the thinning smoke. Her carbine was back in her grip, though her knuckles were blistered and raw where the radiant flash had caught her leather gloves.

She walked toward the gateway, but stopped two paces short.

A high-pitched chime sounded from the shattered console. Then another. Across the ceiling, the amber emergency strobes flickered once and shifted to an angry, persistent violet.

Dario wiped soot from the face of his handheld diagnostic pad. The numbers on the liquid-crystal display were rolling upward in a frantic, unbroken blur.

Minus fifteen.

Zero.

Plus one point four.

"The thermite," Dario whispered.

The air around them was no longer cold. It was humid, rank, and warm, carrying the thick stench of rotting musk and melting glacier mud. On the diagnostic screen, the digital readout settled on positive three point two degrees Celsius.

A low, resonant tone shuddered through the soles of their boots.

On the shattered console, the terminal screen flickered back to life, cycling past the emergency diagnostic routines to display a single system-wide status notification: Thermal Null Disengaged. Specimen Wing Sub-Four through Eight: Quarantine Void.

Dario stared down at the quartz keycard in his hands. The cooling resin hardened across the gold circuits, solidifying the bypass code that would unlock the descent lifts into the abyss.

Geraldo lowered his hands from his charred sleeves, squinting through the smoke at the glowing prompt. "Quarantine void? What does that mean for the arterial elevator, Dario?"

"It means every specimen latch down to the foundation just released," Dario said, tucking the heavy keycard into his coat. "And the stairs are the only way down."