The Oxygen Flare

What tool was striking the seam, and how long until the expansion bolts sheared clean off the wall? Rosaira Valdez braced one boot against the steel frame of the pharmacy door, watching rust flakes drift down from the ceiling lintel with every concussive thud. She needed the Ward Eight bulkhead to hold until she could isolate the sub-manifold, or eighteen fever-burned bodies from the severed wing would pour straight into the hospital's central core.

A third blow shuddered through the floorplates. The heavy iron plate groaned, the top weld splitting three inches above the floor level with a sound like a rifle crack.

"They brought a gantry arm from the linen bay," Inesira Gomez said, her back pressed hard against the metal shelving. She held a heavy brass flashlight in both hands, the beam trembling across the widening fissure. "That seam was only rated for atmospheric differential, not a four-man battering ram."

Mateo Solano stepped past the breaker cabinet. He reached beneath the left lapel of his surgical coat and drew a snub-nosed emergency flare pistol loaded with a brass percussion slug. He pulled the hammer back until the spring clicked in the narrow hall.

"Stand behind the jamb, Valdez," Mateo said, his voice flat. "When the seam splits another inch, I put six drachms of magnesium directly into the throat. The burn will clear the corridor."

"Put that away," Rosaira said, stepping directly into his line of sight.

"They have twelve hundred pounds of structural steel on that ram," Mateo replied without lowering the muzzle. "In forty seconds they will be inside this annex."

"And the moment your magnesium ignites, the stagnant ether in the ceiling return will detonate," Rosaira said. Her fingers closed over the brass bypass wheel mounted beside the switchboard. "You will blow the primary manifold off its mounts and drop four floors of concrete on our heads."

Mateo stared at the vent duct above them, then slowly uncocked the hammer. "Then your suggestion needs to arrive before the hinges drop."

The bulkhead shuddered again under a massive, synchronized impact. The lower left bolt popped free, ricocheting against the concrete wall with a sharp ping. Through the half-inch gap at the base of the frame, gray smoke curled inward, carrying the foul stench of scorched fabric and sour sweat. Beyond the steel, wet, ragged breathing rattled through the ventilation baffle.

Rosaira did not hesitate. Her mind stripped the corridor down to its bare plumbing. Las Ánimas ran its secondary oxygen line through a two-inch copper run right behind the pharmacy header, pressurized at forty-five pounds per square inch. The purge valve sat directly above her head, its drain nozzle aimed into the narrow intake shaft that fed the exterior crawlway of Ward Eight.

She dragged a heavy aluminum step-stool to the wall. "Mateo. The jumper cables on the battery rack. Strip the clamp off the red lead."

Mateo did not question the order. He crossed the room in two strides, took a pair of heavy wire nippers from his pocket, and sheared the insulation off the auxiliary lead. The copper braided wire splayed like a stiff brush in his fingers.

"The turbine is feeding two hundred and forty volts through the sub-panel," Rosaira said, her hand resting on the bypass wheel. "When I open this line, forty pounds of pure oxygen will flush through the crawlway vent. It will push their draft back into Ward Eight."

"And if you don't ignite it, they simply walk through a cloud of enriched air," Mateo said.

"Give me the live lead."

Mateo handed her the bare copper cable, holding the insulated throat with a thick rubber glove. "Next time you remodel the hospital's ventilation system, Valdez, give me advance notice so I can find earplugs."

"Hold the ladder," Rosaira said.

She gripped the brass wheel with her left hand, bracing her thumb against the valve body. Below her, the bulkhead buckled outward another two inches. The blunt, pitted end of a structural steel I-beam rammed through the widening tear in the lower plating. Fingers, grayed and blackened at the nails by the season's rapid necrosis, clawed desperately around the fractured steel edges.

Rosaira threw her weight into the brass wheel.

The valve broke loose with a sharp hiss. A deafening scream of pressurized gas roared through the overhead conduit, flooding the narrow exterior shaft. The sudden surge of pressure reversed the draft instantly, blowing the incoming smoke backward through the fractured seam.

Rosaira jammed the live copper cable directly against the grounded iron frame of the ventilation grate.

A blinding blue arc snapped between copper and iron.

The spark met the high-velocity oxygen stream with a sharp, hollow crump. A roaring sheet of blue and amber flame surged down the exterior crawlway like a piston stroke. The concussive wave vibrated through the floorplates, knocking the heavy steel ram back out of the gap.

A chorus of startled, guttural shouts echoed from the far side of the bulkhead as the heat scorched the uninsulated crawlway, followed by the clatter of the iron gantry crashing against the concrete floor. The sudden outward pulse of combustion consumed the oxygen in the throat within three seconds, starving the breach and driving the attackers into full retreat down the darkened corridor.

The flame died as quickly as it had ignited, leaving behind the sharp, clean smell of singed metal and burned ozone.

Rosaira closed the bypass valve with a swift quarter-turn, stepping down from the aluminum stool. Her palm was hot through her work glove, but the copper line held steady. On the wall monitor above the switchboard, the site collapse countdown ticked past 07:15:00 in cold red numerals. The seam remained warped, but the corridor beyond was silent except for the frantic scrape of retreating footsteps.

Inesira stepped forward, her flashlight beam cutting through the thinning vapor toward the inspection slit in the center of the reinforced door. "They're falling back toward the lower ramps."

Rosaira stepped to the quartz peephole and looked through.

The emergency red lamps in Ward Eight flickered in the haze. Five figures were stumbling away into the shadows of the west ramp, clutching their arms and faces. But at the rear of the corridor, standing beneath the broken exit sign, one man remained motionless for a single heartbeat.

He was tall, stooped, wearing a torn statistical division coat stained with dark ink across the pockets. In his left hand, clamped tightly against his ribs, was an unburned black aluminum data canister marked with the red crest of the primary registry.

The man turned his head toward the quartz port.

Rosaira recognized the gaunt, hawkish face immediately. It was Gabriel Solares—the hospital's chief clinical statistician, whose formal death certificate had been stamped in the regional archive thirty hours ago.

Solares met her gaze through the glass, his eyes wide, deliberate, and entirely lucid. Then he spun on his heel and plunged into the darkened stairwell leading straight down to the basement morgue.

"He's heading for the sub-levels," Rosaira said, turning away from the bulkhead and tightening the straps on her tool harness. "Get your coat, Mateo. We are going down."