The combustion blower on Retort 1 pulled its charge with a rising, subterranean howl—a violent vortex of air screaming through the intake dampeners that drowned out the background clatter of the cracking hall.
Now.
Arin jammed the hardened pry-taper of his multi-tool beneath the head of the upper-left corner pin securing the louver frame.
He didn't use sudden impact; he wedged the steel taper into the rusted gap, braced his thumb against the rivet plate, and torqued the handle. The calcified iron sheared with a dry, sharp pop that was completely swallowed by the roar of the blower.
He shifted to the second pin.
Pop.
Mira took the bottom fasteners. Using the flat spine of her shortsword as a wedge, she popped the lower pair in two fluid strokes.
Arin gripped the louver frame with both hands, easing the forty-pound assembly inward. He didn't let the metal clatter against the casing; he tilted it forty-five degrees and laid it silently onto the floor of Flue 4-B.
The exhaust port was open: an eighty-centimeter square overlooking the floor of Cracking Battery 3.
Directly below the opening, four meters down, sat the cold, dead bulk of an inactive pre-heater. Its structural casing was reinforced with horizontal angle-iron braces stepping down at two meters and one meter from the floor—an industrial ladder built into the machine’s chassis.
"I take lead," Arin whispered, checking his pack clearance. "Follow my hand placements on the iron."
Mira nodded once, blade sheathed at her hip, hands free.
Arin slid through the opening feet-first. He caught the top structural flange of the pre-heater, hung by his fingertips for half a second, and dropped his boots onto the two-meter cross-brace.
The angle-iron took his weight with a faint, muted groan. He stepped smoothly down to the one-meter brace, dropped to the stone flagstones, and rolled into the dense shadow between the pre-heater and the basalt wall.
> [CURRENT STAMINA: 78 → 74/105]
Mira dropped behind him, her boots landing without a sound.
The air on the floor was suffocating. Radiating outward from the glowing fireboxes of the active retorts, the ambient temperature hovered around forty-three degrees Celsius. Greasy black soot settled on Arin’s skin like wet wool, mixing with sweat to form dark streaks down his neck.
Through the gaps between the pre-heater tanks, forty meters of open floor stretched toward the western wall.
Above, on the suspended gantry, the rhythmic, metallic clinking of Tyr’s iron-shod boots echoed over the machinery:
Step. Clink. Step. Clink.
Arin leaned his temple against the cold iron of the inactive tank, his heightened Perception tracking the overseer’s cadence.
Tyr paced at roughly one pace per second. Thirty meters of catwalk. That gave roughly thirty seconds of forward transit, eight seconds to turn at the central steam manifold, and roughly thirty seconds back.
"Roughly thirty-second window," Arin murmured. "Retort 1 through 3 are on our side. We move from tank shadow to tank shadow. Low profile. Keep your head beneath the steam conduits."
"What about the track gangs?" Mira breathed, her chin angled toward the central aisle.
Fifteen paces away, two collared laborers were shoveling crushed shale into the feed hopper of Retort 2. Their iron guide-chains dragged across the stone with a rhythmic skrrt-skrrt.
"They don't look up," Arin said, watching their movements. "A man surviving on a chain only looks at the shovel."
Overhead, Tyr’s boots struck the expansion joint at the far southern turn.
Clink-clank.
The overseer paused, turning his heavy bulk toward the slag pits.
"Move," Arin breathed.
They broke from the pre-heater shadow, staying low in a tight, kinetic scuffle. Arin kept his boots centered on the expansion seams between the flagstones where shale dust dampened footfalls.
They crossed the first twelve meters in four seconds, sliding into the narrow service alcove behind the cylindrical skirt of Retort 2.
The heat here was blinding. The outer skin of the distillation tower radiated over sixty degrees, warming the canvas of Arin’s pack until the nylon smelled of hot plastic. Sweat poured into his eyes, stinging with salt and soot, but the fifteen-percent thermal tolerance passive kept his core temperature buffered:
> [CURRENT STAMINA: 74 → 66/105]
Beside the hopper, five paces from their hiding spot, one of the collared laborers paused mid-shovel.
The man was emaciated, his cheekbones jutting through gray, soot-streaked skin. His bare arms were a network of healed third-degree burns from furnace backdrafts. As he swung his shovel to scrape another load of shale, his sunken eyes tracked across the alcove.
He saw Arin.
Arin froze. His hand didn't drop to his dagger; his posture remained completely motionless, his eyes meeting the laborer’s hollow gaze.
For two agonizing seconds, the cavern hung in suspension. The laborer’s throat worked, his scarred, mutilated neck tightening beneath the heavy iron collar.
Then the man’s eyes flicked up to the catwalk overhead. A shudder passed through his ribs. Without a sound, he drove his shovel back into the shale pile, turned his shoulders away from the alcove, and dumped the load into the hopper with deliberate, exaggerated noise.
A survivor, Arin registered. He knows that seeing something unusual gets a chain whipped.
Overhead, Tyr’s boots began their return march:
Step. Clink. Step. Clink.
Arin and Mira remained pressed flat against the curved iron skirt, letting the overseer's silhouette pass directly above them on the gantry grating. The heavy, square head of Tyr's spud bar swung in a slow, hypnotic arc, its sharpened chisel tip catching the orange glow of the burn-off flares.
When the boots reached the northern turn, Arin signaled.
They surged forward again, crossing the gap between Retort 3 and 4.
Just as Arin’s boot hit the flagstones behind Retort 4, a sharp, mechanical clack echoed from the tower's overhead pressure head.
SHHHHHH-BOOM.
An automated pyrolytic relief valve cracked open twenty feet above them, venting an explosive plume of superheated, oily white steam directly into the aisle.
The blast wave of boiling vapor roared across the ceiling, rolling downward in a choking thermal curtain. The temperature spiked violently, surging past fifty degrees in less than three seconds.
> [ACUTE THERMAL FLASH DETECTED: 52°C (125°F)]
> [METABOLIC TAX: SEVERE SWEAT EVAPORATION]
> [CURRENT STAMINA: 66 → 54/105]
Arin seized Mira’s shoulder, driving her down behind the heavy cast-iron flange of Retort 4's cold-feed line. He pulled the collar of his shirt over his mouth and nose, breathing shallowly through the coarse cotton to prevent the superheated vapor from scorching his airway.
Above them, the clinking of boots stopped abruptly.
Tyr had halted on the gantry.
The heavy iron grate creaked directly over their heads as the overseer leaned his massive forearms against the safety railing, glaring down through the steam cloud at the base of Retort 4.
"Idiots!" Tyr's voice boomed down like thunder, thick with coal smoke and rage. "Watch the secondary draft! You choke the pre-heaters again and I'll toss two of you into the firebox!"
Through the gaps in the iron deck above, Arin could see the soles of Tyr’s steel-toed boots less than three meters overhead. A loose flake of red rust dislodged by the overseer's shift drifted down through the grate, landing softly on Arin’s knuckles.
Arin did not move. He did not breathe. He held his frame in complete, rigid isometric suspension, letting his Endurance 7 engine absorb the metabolic debt:
> [CURRENT STAMINA: 54 → 50/105]
Tyr spat over the rail—a dark glob of chewing tobacco that hissed against the hot casing of the tower—then turned with a grunt and resumed his heavy, lumbering stride toward the southern terminus.
Step. Clink. Step. Clink.
"Go," Arin whispered through the cloth.
They broke from Retort 4, staying deep in the steam wash, and sprinted the final fifteen meters behind Retort 5 and 6.
Ahead, the basalt floor ended at an iron maintenance curb.
Running parallel to the western wall, sunken sixty centimeters below the flagstones, was the Cold Condensate Return Trench.
The channel was a meter wide, carrying a sluggish stream of cool condensation water drained from the lower cooling jackets. The temperature drop here was immediate—the chilled water brought the surrounding air down to twenty-six degrees, generating a thick, low-lying ground fog that blanketed the trench like dry ice.
Ten paces to the north, sitting on an overturned kerosene drum right above the trench's intake mouth, was Korin.
The Level 3 sentry had his back half-turned, his arbalest resting across his thighs, slowly dragging an oily whetstone along the bevel of his boarding pike.
Scrape. Scrape. Scrape.
Arin slipped over the iron curb, lowering his boots silently into the shallow, flowing water of the trench. The water was six inches deep, shockingly cold against the scorched rubber of his boots, soothing the throb in his bandaged calf.
Mira slid in beside him, crouching low so the rolling ground fog swallowed her torso.
They remained crouched in the trench for nearly a minute, letting the cold water bleed the furnace heat from their bodies. The cold air hit Arin's lungs like clean oxygen. His heart rate dropped steadily, the oppressive thermal stress falling away as the blistering furnace heat of the hall was cut off by the lip of the trench:
> [STAMINA RECOVERY TICK: +1 / 8 SECONDS]
> [ELAPSED TIME: ~48 SECONDS]
> [CURRENT HP: 84/125]
> [CURRENT STAMINA: 50 → 56/105]
Fifty-six stamina. Health holding at eighty-four.
The trench stretched westward, tunneling beneath a low concrete lintel toward the rumbling dark of the Central Transport Tube.
Arin glanced back through the swirling white mist at the base of the cracking towers. Behind them, Cracking Battery 3 continued its deafening, indifferent industrial roar, the chained laborers shoveling shale, Tyr pacing his gantry, and Korin turning his whetstone.
Not a single alarm had sounded.
Arin reached to his pack, ensuring the heavy Salvaged Pike Head was snug in its loop, then turned toward the dark current flowing downstream.
"Keep your head below the lip," Arin whispered. "Let's see what's on the rail."