Ignition

The chain links under Soshi's boots rattled against the iron frame of the gantry. Thirty feet below us, the magma pool surged against the throat of the vent, throwing a red glare across his frozen mask.

"Put the mallet down, knapper," Soshi said. His voice was raw gravel, thick with the dry cough of a man who had eaten boiled frost-moss for three winters. "You break that stone, you roast us all. You don't have the stomach to cook your own bloodline."

"I don't have a bloodline on this tier," I told him. "Just an unpaid tab at the brewery and three clients who never settled their deposits."

I kept my grip steady on the bone billet. The bronze punch was already seated three inches into the primordial prism's forty-five-degree conchoidal plane. All it needed was three ounces of forward momentum delivered at ninety degrees to the drive line. Stone didn't negotiate with raiders. Stone didn't care if an invader had walked three hundred miles across ice sheets just to steal a hot meal.

"Drop it," Soshi barked, taking another step. The broad iron cleaver in his fist rose, its nicked edge catching the red glare. Behind him, sixteen elite frost-troopers crowded onto the narrow planking. Their river-ice armor was already weeping grey slush onto the hot basalt below, hissing like a nest of scalded pit-vipers.

"Yamato always said masterwork glass was too brittle for serious work," I muttered, planting my heels against the rim of the draft chute. "He wanted thick iron. Iron bends when you step on it. Glass just cuts until there's nothing left to bleed."

I brought the bone billet down.

The impact didn't make a loud crack. It made a clean, musical chime, like a temple bell dropped onto a stone hearth.

A white fracture line raced through the heart of the ten-pace prism. The conchoidal wave sheared through the primordial obsidian, opening a six-inch fissure along the throat of the vent. The back-pressure of four hundred atmospheres of subterranean heat found the seam instantly.

The thermal release did not roar. It screamed.

A blinding plane of incandescent orange light erupted from the fracture. It hit the underside of the iron gantry with the speed of an uncoiling spring. The heavy river-ice slabs lashed to the raiders' armor didn't have time to melt into water. They converted directly to high-pressure steam in the span of a single heartbeat, exploding outward and ripping through their boiled hide padding.

Soshi lunged forward with his cleaver, but the metal warped before the swing crossed half the distance. The iron blade turned the color of ripe persimmons, drooped toward the floor, and tore free from its brass hilt.

The gantry gave a long, shuddering groan as its anchor pins sheared out of the basalt walls.

I didn't stay to watch Soshi hit the magma pool. I threw myself backward into the narrow mouth of the auxiliary draft chute, tucking my shoulders tight against the soot-caked stone.

The updraft caught me like a giant fist. Superheated air and pulverized pumice hurled me up the three-story chimney, scraping skin from my elbows and knees as I scrambled for the carved rungs. Below my boots, the deep flue collapsed in a rolling thunder of collapsing basalt. The directional wave funneled every grain of volcanic ash straight up through the central exhaust columns, turning the Fourth Terrace shafts into roaring chimneys of grey grit.

I hauled myself over the rim of the forge trapdoor, coughing black sludge, and collapsed onto the workshop flagstones.

The forge was quiet now.

The battering rams had stopped. The raiders who had breached the outer barricade were gone, or buried beneath the choking fog spilling from the floor vents. Heavy grey ash was already drifting through the shattered doorway like winter snowfall, coating the anvil, the quench tubs, and the dead.

Yamato was slumped against the water trough where I had left him. The boar-spear still jutted from his stomach, but his eyes were open, tracking my boots through the gloom.

"You took your time," Yamato wheezed. A bubble of pink froth broke on his cracked lower lip. "Did you break it?"

"Clean through the core," I said, wiping soot from my eyebrows with the back of a scorched wrist. "The gantry fell. Soshi's vanguard is cinder."

Yamato let out a dry rattle that might have been a laugh if his lungs had any air left. "Good. The big bastard owed me a return match in the pit."

He looked toward the open terrace archway. Beyond the forge door, the Great Stair of the Fourth Terrace was silent. There were no shouts of triumph, no war cries from Kento's remaining guards. There was only the dry, relentless rustle of hot ash falling six inches deep across the district.

The exhaust chimneys had done what the primordial prism commanded. The directional blast had roasted the lower tunnels and sealed the core vents, but the resulting ash plume had billowed straight into the residential caverns. It choked the mushroom beds. It smothered the terrace greenhouses. It coated every warm air vent in two feet of suffocating volcanic dust, severing the heat conduits that kept this tier alive.

Across the room, Jiro dragged himself upright from the masonry wall, leaning heavily on a splintered pike. His left shoulder was crushed and wrapped in blood-soaked wool. By the shattered doorway, three soot-stained refugees huddled against the jamb, clutching damp rags to their noses.

Kento pulled himself up beside the stone anvil, limping on a makeshift crutch, his speared thigh bound in tight leather. He stopped where he stood, staring past me toward the smoking flue hatch, then out at the grey, dying terrace.

"The core is safe," Kento said. His voice was hollow, stripped of the warden's bark. "The raiders won't reach the fifth tier."

"No," I replied, sitting back against the base of my cold anvil. "They won't reach anything."

Kento looked at the ash piling against the shop's doorframe. The warm air that had sustained the Fourth Terrace for three generations was already thinning, replaced by the biting draft drifting down from the northern rim breach. In two days, without the flue conduits open, the rock beneath our feet would freeze solid.

"You knew this would happen," Kento whispered. He didn't raise his voice. He didn't have the strength, and neither did the men behind him. "You knew the draft would vent through our quarter."

"It was your quarter or the whole crater," I said. "You asked for eighty blades to hold a wooden gate. The blades broke. I used what was left."

Yamato's head tilted back against the cedar rim of the quench tub. His breathing had slowed to a shallow, rhythmic rasp, his scarred hands resting limp across the shaft of the spear in his gut.

"Don't bicker with him, Kento," Yamato murmured, his eyes fixed on the soot-blackened ceiling timbers. "He's a knapper. When he hits a fracture line, the stone splits where it's supposed to. He doesn't pay for the chips."

Yamato's chin dropped to his chest. The shallow breathing did not resume.

The workshop settled into a silence broken only by the soft, steady patter of ash sifting through the roof slats.

Kento stood in the doorway for a long time, watching the grey drift build against the dead champion's boots. Then he turned his back on me and hobbled out into the ruined street, leading what remained of his people toward the upper stairs.

Nobody offered me a hand. Nobody told me to follow.

I picked up my bone billet from the floor, blew the grey powder from its polished grip, and tucked it back into my leather sash. The air in the shop was growing colder by the minute, but my hands were steady. I had eighty pounds of raw nodules waiting in the third-tier caches, and a whole city of freezing survivors who would soon need new knives.