The Nitric Deluge

"Lever," Riosbh said. She grabbed the two-foot iron bar Colmhaign had carried from the bulkhead.

She wedged the chisel end of the bar between two spokes of the frozen wheel, jamming the flat against the structural rib of the catwalk truss to create a fulcrum. "Take the handle, Colmhaign! Pull toward the stanchion!"

Colmhaign gripped the extended end of the iron lever. Murchadh scrambled up the last rungs of the ladder, his boots slamming onto the grating as he threw his weight onto the bar beside Colmhaign.

"Together," Riosbh ordered, planting her boot against the valve body to brace the assembly. "On three. One. Two. Three!"

The two men hauled back on the iron lever with a collective, ragged heave.

For a terrifying heartbeat, the iron bar bowed under the torque, the rusted metal screeching. Then, with a concussive crack that reverberated through the steel truss, the frozen spindle broke free.

The wheel spun half a revolution, spraying chips of petrified packing grease into Riosbh’s faceplate.

"Keep turning!" Riosbh shouted, grabbing the rim of the wheel with her bare canvas mittens and spinning it clockwise against the grinding thread. "Ten full turns to seat the gate!"

Three. Four. Five.

The ceiling nozzles began to hiss violently, spitting a fine, stinging rain of nitric acid that sizzled against their canvas hoods and the metal catwalk beneath their feet. A drop struck Riosbh's shoulder, and she felt the sudden, alarming warmth of canvas reacting with concentrated acid.

Six. Seven. Eight.

The resistance on the wheel grew brutal as the gate wedge met the surging fluid column. Riosbh, Colmhaign, and Murchadh strained together, their combined weight forcing the iron wheel through its final rotations until the spindle bottomed out with a solid, metallic thud.

Above them, a deep hydraulic shudder ripped through the ceiling. The swollen delivery hoses collapsed back into slack rubber loops. The stinging spray from the overhead nozzles sputtered, choked, and died, replaced by the hollow gurgle of five hundred gallons of acid draining backward through the emergency overflow into the exterior ballast tanks.

Murchadh slumped against the catwalk railing, his breath rattling wetly through his rebreather. "Did we... did we kill it?"

"The acid is isolated," Riosbh breathed, her gloves trembling as she let go of the iron wheel. Her canvas sleeves were steaming where the mist had settled, but the heavy vulcanized layers had held. "The primary deluge is dead."

"We aren't clear yet," Colmhaign said.

He was looking toward the ceiling vents above the manifold box. Deprived of its intended discharge through the spray nozzles, the pressurized air trapped in the intake culvert had nowhere to go. The automated exhaust dampers, designed to balance internal pressure during a purge, began to chatter wildly.

A sharp bang echoed through the ductwork as a rupture disc blew out in the exterior vent stack.

Immediately, the air in the vestibule began to move. The sixty-kilopascal pressure within the station dropped steeply as the unsealed exhaust flue acted like a giant syringe, sucking the vestibule’s atmosphere out toward the low-pressure exterior culvert. The yellow spore fog swirled into a violent vortex, whipping around their helmets and dragging at their legs.

"The blow-off disc failed," Riosbh said, raising her voice over the rising roar of escaping air. "The station's venting into the gorge!"

"The inner doors won't open while the vestibule is depressurizing," Murchadh yelled, pointing down toward the main habitat hatch. The digital access panel beside the heavy blast door was flashing a solid, unforgiving crimson: BAROMETRIC FAULT - LOCKDOWN ENGAGED.

"We don't go through the habitat doors," Riosbh said. She leaned over the catwalk rail, shining her light down into the far corner of the concrete floor.

Beneath the swirling fog, nearly hidden by the caustic puddles, sat a heavy, round iron deck plate marked with the stamped symbol of the station's lower biological research division.

"The lower bio-labs," Riosbh said, dropping down the ladder rungs two at a time. "The drainage sump connects directly to their filtration sublevel. It has a manual mechanical hatch that doesn't rely on the station's automated pneumatic bus."

Colmhaign and Murchadh hit the deck behind her. The roar of the venting air was deafening now, the atmospheric pressure dropping fast enough that Riosbh felt her suit canvas ballooning slightly as the internal pressure pushed against the thinning ambient room air.

She reached the iron deck plate and dropped to her knees. The hatch was secured by four heavy perimeter dogging lugs.

"Murchadh, the spanner! Colmhaign, the lever!"

They worked with frantic, practiced efficiency. Murchadh hammered the first two dogging lugs loose with the heavy bronze head of his spanner, while Colmhaign used the iron lever to pry the rusted locking bar clear of its retaining tooth. Riosbh seized the central wheel, hauling it counter-clockwise until the internal cam disengaged with a deep, echoing clunk.

Together, Colmhaign and Riosbh heaved the heavy iron lid upward.

A blast of freezing, bone-dry air rushed out of the dark opening, carrying the sharp, mineral smell of dormant limestone and undisturbed dust—completely free of the yellow spore stench that choked the vestibule above.

"Murchadh, down first," Colmhaign commanded, gripping the mechanic’s shoulder harness and guiding him into the narrow shaft. "Find the maintenance platform and clear the base of the ladder."

Murchadh didn't argue. He swung his legs into the void and descended into the blackness, his boots clanging against the vertical steel rungs below.

"Riosbh, you're next," Colmhaign said.

Riosbh gripped the rim of the manhole, looking down into the dark sublevel, then back at the swirling, acid-scorched room they were leaving behind. Overhead, the sheet-metal ductwork was buckling inward under the violent draft of the exterior breach, iron rivets popping like pistol shots as the ceiling frame warped.

She slid through the hatch opening, finding the cold rungs with her boots, and descended four steps until her head was level with the deck.

Colmhaign lowered himself into the shaft above her, holding the heavy iron lid with one braced arm.

"Take the inner dogging handle," Colmhaign told her, his voice steady even as the floor around them trembled under the structural strain of the imploding ductwork. "When I drop the plate, throw the latch."

Riosbh reached up, her gloved fingers wrapping around the cold iron handle on the underside of the hatch.

Colmhaign pulled the lid down.

The heavy steel plate slammed home with a deafening, final clang, cutting off the roar of the depressurizing vestibule and plunging them into absolute, suffocating darkness.

Riosbh hauled the inner dogging handle down until the hardened steel teeth bit deep into the underside rim, locking the hatch firmly against the frame.

Beneath them, deep in the silent belly of Station Two's lower bio-labs, the faint, low hum of an isolated backup generator thrummed through the iron rungs, steady and patient in the dark.