The First Blast of Frost

Falling down a vertical flue is an exercise in calculated friction, provided you intend to reach the basement with your marrow intact. If you spread your elbows too wide, the corners of the brickwork will snap your collarbones like dry kindling; tuck too tight, and you hit the hearth as fifty pounds of red tallow.

I didn't tuck. I had four stories of grease-choked chimney to arrest my plunge, forty pounds of pressurized copper compressor tearing at my shoulder harness, and an apprentice tumbling three yards ahead of me in the dark.

I drove the steel blade of my flat soot-scraper against the south brick course and kicked both boots out hard, ramming my copper-plated heels into the north wall.

Iron met vitrified soot with a shriek that rattled through my jaw. Sparks sprayed across my goggles, blinding me with yellow flashes against the greasy dark. The twin brine cylinders on my back dragged at my spine, threatening to wrench my shoulders out of their sockets, but the copper cleats bit deep into the crumbling mortar joints. Scorched leather filled my nostrils as friction burned away the soles of my work boots.

Five feet. Ten feet. My speed slowed from a fatal plunge into a bone-jarring skid.

Below me, a ragged cough cut through the hiss of falling soot.

"Hold the damper!" I roared, the dust coating my tongue like bitter flour.

Lázaro was wedged twenty inches below me, sprawled across a rusted cast-iron flue vane that projected from the masonry between the third and fourth floors. His small hands were bloody, clawing at the oxidized flange while his legs kicked over empty air. The mounting bracket groaned under his weight, flakes of red rust showering down the shaft toward a dull heat rising from the depths.

I jammed my left scraper into a horizontal mortar gap, locked my knee against the opposite wall, and reached down with my right arm.

My gauntlet caught the coarse canvas collar of his sweep tunic. I hauled upward with my shoulder, ripping him off the collapsing iron plate just as the bracket sheared clean and clattered down the chimney.

"Got you," I grunted, dragging his trembling ribs against my hip and the soot-caked brickwork. "Heels on the flue seam. Don't look down."

Lázaro gasped, his breath whistling through lungs fouled by sulfur. "Master... the heat. It's climbing."

The air didn't smell merely of old ash anymore; it stank of rendered grease and high-pressure coal-gas. A thick wave of heat surged up the shaft, hot enough to singe the frayed threads on my cuffs. The glow beneath us was not a bed of coals. It was a cluster of six dull crimson eyes set into a spade-shaped skull of obsidian chitin.

The scout Ash-Weaver was four feet of armored cruelty, ascending the vertical bricks with horrific speed. Eight jointed limbs tipped with curved iron barbs punched into the masonry, levering its bulk upward without a pause. Between its serrated mandibles, a pool of thick pitch bubbled, stoked by the internal fire in its belly. It didn't scuttle like a common cellar spider; it climbed with the rhythmic, pneumatic precision of a factory piston, drawn toward the draft our bodies blocked.

"Sleeve over your mouth, boy," I said, keeping my voice level. "Now."

"Master, the compressor—"

"Sleeve over your face and close your eyes."

In a twenty-inch chimney, a sweep cannot swing a club or brandish a pick. You have leverage, a few inches of clearance, and whatever foul chemical compound you bought on credit at the docks.

I reached behind my ribs with my free hand, unclipped the heavy brass wand from my chest harness, and brought the nozzle forward over my shoulder. The braided copper feed line groaned under tension. My thumb found the cock on the manifold. The needle on the pressure gauge hovered at three bars. If the radiant heat from the climbing beast boiled the chemical salt solution inside the tanks or softened Inéz's lead solder, the twin copper cylinders would detonate like a municipal trench mortar, turning both sweeps and spider into vaporized paste.

I had perhaps five seconds before the shell absorbed too much heat.

The Weaver halted four feet below my boots. Its flat head tilted, pincers clicking in a wet, rhythmic rattle. It tasted the down-draft we displaced, its bloated abdomen pulsing with dull furnace light.

Its jaws spread wide. A knot of burning pitch welled in its throat, preparing to vomit a geyser of boiling slime straight up the chimney.

I didn't shoot at its armored head. A sweep doesn't scrub soot off the chimney crown; he cuts the draft at the throat.

When the beast lunged upward, mandibles flared to spit its liquid fire, I drove the brass wand straight down between my boots. I ignored the radiant blast that blistered my knuckles through the leather. I rammed the nozzle past its snapping mandibles, directly into the soft, pale flesh of its gullet, and slammed the release lever flat.

The brine rig hissed with the savage fury of super-cooled salts and compressed ammonia expanding into an open furnace.

A dense cloud of pale, chemical frost erupted from the wand. The brine compound vaporized upon contact with the heat, dropping the shaft's temperature forty degrees in an instant. The boiling pitch in the beast's maw never ignited; it froze solid, crystallizing into black gravel with a crackle like shattered glass.

The scout emitted a high-frequency whistle, a piercing shriek that resonated through the iron damper brackets. Frost raced across its chitin plates, turning the gleaming black armor into a milky, brittle rind. Its front legs locked rigid as the sub-zero foam froze the dark fluid in its veins.

"Die in the cold, you coal-thief," I muttered, and stomped my copper-plated heel onto its frosted brow.

The brittle carapace gave way like thin lake ice under an iron boot. The scout's skull caved in with a dull crunch, showering frozen black crystals into the void. Its legs tore free from the brickwork, and the rigid carcass tumbled backward down the chimney, bouncing off the masonry ledges until it struck the basement soot-trap four stories below.

Silence fell across the shaft, cold and heavy, broken only by the hiss of venting foam and Lázaro's ragged breathing.

I eased the brass lever back. The gauge needle rested at two bars. Cold bled through the brass tube into my gauntlets, frosting the metal white despite the warm air swirling around us.

"Lázaro," I said, nudging the boy's ribs with my elbow. "Report. Anything broken?"

He blinked soot from his eyelashes, pressing a blackened hand against his chest. "Sore, Master. But nothing shifts when I cough."

"Good. Landlord Trilla charges three groats for every cracked brick we leave behind. I'm not paying for your broken bones out of my clean-air fund."

Lázaro let out a wheezing chuckle that dissolved into another dry cough. "You broke the bricks with your heels, Master. Not me."

"My boots have a municipal sweep license to break brick. Your backside does not."

I reached to my tool belt, pulled two forged iron wedges, and drove them deep into the mortar seam beneath Lázaro's boots, giving him a stable footing against the wall.

The immediate fall was halted, but the air remained thick with the sweet, sickening odor of raw coal-gas. The scout was dead, yet its dying whistle had not died with it. That high-frequency shriek had traveled down the cast-iron bypass pipe we discovered above, echoing through the iron headers of the district mains.

From deep within the building's foundation, an answering resonance stirred.

It began as a low metallic hum vibrating through the chimney bricks. Then came the scratching: a rhythmic, synchronized scraping of hundreds of barbed limbs against the interior walls of the subterranean gas mains. The scout's death cry had agitated the colony feeding in the dark beneath Casa Trilla.

Lázaro stiffened, his fingers digging into my coat sleeve. "Master... listen."

"I hear it."

Above us lay four stories of greasy, sulfur-slick brick and a sheared safety line. Below us, the main line was waking up.

Right beside my hip, where the third-floor damper had torn loose, the cracked soot revealed an old municipal inspection hatch bolted to the masonry. Its iron wingnut was rusted, but the hinges were sound.

Lázaro looked up at me, his eyes wide in the dark. "Do we climb back to the roof, Master?"

I tapped the brass scraper against the inspection hatch's iron latch, listening to the swelling hum of claws in the lower pipes.

"Nobody pays a sweep for half a flue," I said, and twisted the wingnut free.