The Intake Stroke

Colmhaign reached up, his fingers finding the iron rung bolted into the rock wall beside the door. He hauled his boots onto the narrow ledge, two feet above the grating, bringing his chest level with the sniffer housing.

Inside his helmet, the rhythmic scrape of his own rebreather diaphragm was the only steady sound. His suit manometer read ninety-four kilopascals. The ambient gauge on his wrist showed eighty-two kilopascals and climbing as the heavy atmospheric wave approached.

"Timer," Colmhaign said.

Riosbh held her chronometer against the quartz port of her mask. "The exhaust click was twelve seconds ago. Next intake stroke in sixty-eight seconds."

"Murchadh, mount the tube."

Murchadh reached up with his long spanner, pressing the greased copper cone over the sniffer's intake screen. The tallow squelched, forming a gummy, airtight seal against the oxidized iron rim. He braced the tube with his shoulder, leaning his full body weight against the rock wall to hold the fitting true against the wind that howled down the gorge.

"Forty seconds," Riosbh called out. Her voice was steady now, falling into the familiar cadence of a laboratory trial. "Barometric pressure at the threshold is eighty-four point five kilopascals. Differential is nine point five."

Colmhaign took the free end of the copper line in his gloved left hand. He guided it down to the brass petcock on his right thigh. The fitting was stiff with cold grease. He used his thumb to scrape the ice from the threads, then aligned the copper sleeve with the outlet nipple.

"Twenty seconds," Riosbh said. "Spore density in the lower culvert is ninety-eight parts per thousand. The front is two hundred yards out."

Colmhaign did not look down the rail. He kept his right hand on the brass wing-nut of the drain valve. His fingers felt numb through the triple-layered vulcanized canvas, but he could feel the faint, mechanical vibration of the internal bellows against his ribs.

Every breath he took in was dry, scrubbed through calcium hydroxide and chilled iron coils. In the military logistics corps, he had been taught that human respiration was an expenditure line—so many liters of oxygen converted to metabolic heat per hour, budgeted against transport tonnage. Deserting that command had not been a matter of panic; it had been the cold realization that corporate ledgers treated human lungs as disposable gaskets while protecting synthetic freight. Here, thirty-seven milligrams of alveolar moisture per liter was the only currency the machine recognized. To the station's logic board, a cloud of unscrubbed spores was noise; a warm pulse of expired carbon was an unmistakable signal of human life.

"Ten seconds," Riosbh whispered. "Eight... seven... six..."

A sharp, metallic clack echoed inside the armored iron cowl.

"Intake solenoid open!" Riosbh shouted.

Colmhaign twisted the brass wing-nut a quarter-turn counterclockwise.

The valve unseated with a sharp hiss.

Inside his suit, the pressure plummeted. The canvas around his legs instantly tightened, collapsing against his shins and thighs as the internal air was sucked through the copper tube by the sniffer's internal vacuum pump. On his wrist, the manometer needle jerked backward: ninety-four... ninety-one... eighty-seven kilopascals.

Colmhaign clamped his teeth shut, forcing his diaphragm down against his abdomen, pumping the air from his lungs directly into the rebreather's lower circuit. He felt the intense, burning cold of the outer gorge air trying to force its way back through the valve threads, chilling the metal against his groin. If he lost another four kilopascals, the suit's internal positive pressure would collapse entirely, and the ambient culvert air would invert the rubber check-valves.

One second.

Two seconds.

Three seconds.

Inside the sniffer housing, a tiny quartz window flickered with a faint, cherry-red glow. The platinum-iridium element was heating the sample. The smell of scorched fat and vaporized moisture drifted through the tiny exhaust vents.

Four seconds.

The solenoid fired again with a heavy, deadened thump. The intake shutter slammed shut.

Colmhaign instantly wrenched the brass wing-nut clockwise, slamming the drain needle back into its lead seat. He tightened it until the brass threads groaned, then smeared a handful of tallow across the junction to seal any microscopic weeping.

His wrist gauge stood at eighty-six kilopascals. The ambient culvert pressure had reached eighty-six point two.

For two seconds, the suit felt loose, dead, and slack against his skin. Then the rebreather's secondary oxygen booster hissed, feeding a five-second burst of compressed gas into his chest loop, lifting the internal pressure back to ninety-two kilopascals.

Colmhaign dropped from the ledge, his boots hitting the iron grating heavily. He leaned his hands against his knees, drawing two shallow, ragged breaths through the dry mouthpiece.

"Did it register?" Murchadh asked, pulling the copper tube free from the cowl. A string of burnt tallow stretched between the metal and the rock. "Or did the Westinghouse decide your lungs don't meet corporate specifications?"

"The specifications haven't changed in thirty years," Colmhaign said. "Wait for the relay."

The yellow wall of the Breath-Tide slammed into the exterior stanchions of Station Two.

The wind went instantly deafening. The sound was the physical impact of billions of micro-crystallized spore husks battering the iron plating. The visibility vanished; the gorge, the rails, the distant pylons of Stanchion Fourteen disappeared behind a thick, churning curtain of ochre dust that hammered against their helmets like buckshot. The canvas sleeves of their suits began to hiss as the abrasive cloud scoured the vulcanized coating.

"Colmhaign!" Riosbh cried, bracing her boots against the sill as the wind threatened to slide her across the slick grating. "The lamps aren't changing!"

Colmhaign stood motionless against the gale, his eyes fixed on the quartz housing. "Wait for the logic relay to clear the sample."

Seven seconds. Eight seconds.

Inside the mountain, deep within thirty feet of solid basalt and steel reinforcement, a massive high-voltage relay cracked like a rifle shot.

The three amber lamps above the lintel died simultaneously.

A single, brilliant green indicator flared into life inside an armored quartz housing above the center jamb.

From within the rock wall came the slow, terrifying groan of hydraulic accumulator tanks releasing sixty thousand pounds of pressurized oil into the lifting cylinders. The five-inch manganese slab shuddered. The six locking wedges in the bedrock retracted with a series of concussive thuds that rattled the teeth in Colmhaign’s jaw.

"Clear the sill!" Murchadh bellowed, grabbing Riosbh by the shoulder harness and dragging her toward the door frame.

The bottom edge of the fifty-ton storm gate broke its seal against the bedrock with a wet, tearing screech.

A violent, hurricane-force vortex of air erupted around their boots. Station Two’s outer vestibule was maintained at an internal vacuum of seventy kilopascals during Level Four containment to prevent airborne escape. The moment the seal parted, the eighty-six-kilopascal air of the culvert rushed into the gap with the force of an exploding boiler.

Colmhaign was lifted off his feet. The atmospheric draw dragged him forward across the threshold, his knees slamming into the bronze guide track of the inner vestibule. Behind him, Murchadh and Riosbh were pulled through the churning yellow vortex, tumbling onto the diamond-plate floor of the airlock in a tangle of canvas limbs, copper pipe, and rattling iron tools.

With them came thousands of cubic feet of unscrubbed culvert air—a dense, roiling plume of yellow spore dust that filled the twenty-foot concrete vestibule like thick mustard smoke.

Above them, the counterweights dropped.

The manganese storm gate slammed back down into its bedrock shoe with a ground-shaking crash that severed the howling wind of the gorge mid-note, sealing the three of them into the absolute, echoing dark of the isolation lock.

For three seconds, there was only the sound of their own ragged breathing and the ticking of cooling metal.

Then, from the ceiling twelve feet above their heads, sixteen high-pressure decontamination nozzles spun outward on pneumatic arms.

A harsh, rhythmic klaxon began to pulse from the bulkhead walls, accompanied by the violent, sulfurous glare of four crimson strobe lights.

A mechanical voice, dead and synthesized, crackled through the armored horn speaker above the inner door:

Bio-contaminant volume exceeds Class-Four tolerance. Vestibule isolation confirmed. Commencing primary caustic wash in five seconds.

A hiss of pressurized liquid echoed through the manifold pipes overhead.

Colmhaign rolled onto his side, his flashlight beam cutting through the yellow fog to find the inner emergency bulkhead. Beside the hatch stanchion, the station's heavy iron decoupling lever hung locked in its spring-bracket. He wrenched the two-foot bar free with a sharp snap of rusted steel, securing the manual tool they needed to throw the ventilation valves before the acid lines pressurized. Between them and the safety of the main habitat stood thirty feet of concrete deck, two manual decoupling wheels, and an automated deluge system about to spray five hundred gallons of concentrated nitric acid onto their rotting canvas suits.

He gripped the iron lever in his fist and pushed himself to his feet.