The floor of the smelting hall felt like the deck of a sinking ironclad.
Every step Lin Ke took sent a sharp jolt through his hardened knee joints. But the heat from the flags was worse. It soaked straight through the thin woven straw of his sandals. It scorched the calluses on the soles of his feet.
Above them, Fire No. 9 rose four stories into the soot-blackened gloom. A tube-shaped mountain of linked dark rock blocks bound by banded iron hoops three inches thick.
Normally, the stone was the color of dried mud. Tonight, the lower third of the belly was glowing a dull, angry crimson, the heat streaming so wildly that the air ten paces away shone like rippling water.
A deep, groaning screech echoed from the mortar joints.
“The banding is stretching!” a senior slave screamed, dropping his iron tongs and bolting toward the blast doors. “The iron hoops are giving way!”
“Get back to your posts, you dogs!” Overseer Fang shrieked from thirty paces back. His back was pressed firmly against the heavy oak frame of the emergency exit. He brandished his copper whip, but his knuckles were dead white, and his boots were angled for flight. “Anyone who breaks rank is fed to the melted rock waste ditch!”
Nobody listened.
Four more fire slaves threw down their rakes and scrambled across the floor, slipping in lime dust as they clawed toward the exits. They had seen what happened when five hundred tons of molten iron and boiling sulfur melted rock waste blew through dark rock stonework. There would be no bodies to bury. Only black stains burned into the bedrock.
Lin Ke didn’t run.
He stood near the cooling racks, squinting through the blistering rising heat currents. The heat baked his skin dry, making his eyelids sting with every blink.
Diagnostics, his mind registered calmly. Ignore the panic. Read the physical tracking data.
The main stone exhaust channel along the fire spine had cracked near the third floor. White, whistling steam escaped through a jagged upright fissure in the mortar.
The pressure inside the vessel was climbing faster and faster.
Overseer Fang saw him standing still and cupped his hands around his mouth, shouting over the thundering roar: “Seven! You fool! Open the cold air dampers! Pull the master draft lever on the narrow high walkway!”
Fang’s instinct was natural: if an oven is too hot, open the chimney pipe and let cold air in.
Lin Ke’s eyes narrowed.
Open the cold air dampers into a sealed, white-hot reduction chamber full of carbon monoxide?
Branch, Lin Ke commanded internally. Test Fang’s proposal.
In the quiet, suspended theater of his skull, the phantom Lin Ke leaped up the iron ladder to the upper narrow high walkway. His hands grabbed the master draft lever. He threw his weight backward, wrenching the cold-air damper open.
A rush of cold night air slammed down the draft stack into the fire belly.
The test model flashed blinding white.
The sudden influx of oxygen met the high-pressure carbon monoxide and boiled away sulfur. An explosive backdraft blew up instantly inside the firebox.
The three-inch iron bands snapped like rotten twine. Five hundred tons of molten iron erupted outward in a three-hundred-sixty-degree blast wave, vaporizing the narrow high walkway, the slaves, Overseer Fang, and half the smelting hall in less than a second.
Lin Ke shuddered, bile burning the back of his dry throat as the phantom explosion echoed through his nervous system.
He touched the scarred pad of his thumb with the iron metal pen.
“Branch checked: main.”
The physical world rushed back. The fire groaned again—a low, metal scream as another mortar joint buckled near the base.
Seventy seconds left.
“Don’t touch the draft lever!” Lin Ke shouted toward the exit. His voice was hoarse. But carried the flat, clear power of an incident commander cutting through a conference bridge. “If you feed cold air into an unvented chamber, the backdraft will level the ward!”
Fang froze near the doorway. “Then how do we drop the pressure, you idiot? The stone is about to split!”
“We dump the bottom head-pressure first,” Lin Ke snapped. “We blow the melted rock waste latch.”
At the very base of Fire No. 9, three feet above the flat stone slabs, sat an emergency clockwork relief port. A heavy cast-iron swing gate designed to dump raw quartz dust melted rock waste into a recessed drainage trench during total blockages.
It was held shut by a narrowed bronze wedge, intended to be knocked free with a sledgehammer.
Lin Ke sprinted across the scorching flags toward the fire base.
The heat near the hearth was staggering. It felt as though his eyebrows were curling into ash. The hair on his forearms singed with a crisp, crackling sound, filling his nostrils with the reek of burnt protein.
Every breath scorched his lungs like inhaling ground glass.
He reached the tool rack near the crucible trench. His fingers wrapped around a three-pronged iron crowbar four feet long and weighing thirty pounds.
The metal was hot enough to leave faint scorch marks on his palms, but he locked his grip. He ignored the blistering skin.
He lunged toward the base of the fire.
The bronze wedge in the melted rock waste latch was glowing dull red. Over decades of neglect, heavy iron-stone-glass melted rock waste had leaked into the hinge pin. That turned into glass into a solid glassy weld.
Lin Ke jammed the chisel tip of the crowbar into the seam between the bronze wedge and the iron collar.
He threw his entire body weight onto the bar.
The metal didn’t budge. The melted rock waste weld held fast.
Lin Ke didn’t panic. Panic was wasted clock cycles.
He planted his feet on the greasy dark rock floor. His hardened knee joints shrieked under the shearing force, the dead stone deposits in his femurs grinding against his hip sockets.
He didn’t possess spiritual Qi. He couldn’t summon sky thunder or earth-shattering palm strikes.
What he had was leverage, mass, and forty percent of his skeleton made of solid, incompressible iron ore.
He braced his left shoulder against the cold stone of the drainage trench curb, using his own stone-hard leg as a rigid clockwork strut. He brought his right heel up and slammed his leaden boot down onto the flat end of the crowbar with everything he had.
CLANG.
The impact jarred his entire skeleton, sending a sharp blast wave through his teeth.
The glassy weld fractured with a sound like pistol shot.
The narrowed bronze wedge flew outward, spinning across the flags.
The heavy iron swing gate blasted open.
WHOOSH.
A blinding, roaring torrent of liquid sulfur melted rock waste vomited from the lower belly, cascading into the emergency sand trench with the fury of a burst volcano.
The heat was instant and terrible.
A cloud of white-hot steam and boiled away zinc erupted from the wet sand at the bottom of the trench, billowing upward.
Lin Ke twisted his body away, but he was four feet from the mouth.
The scalding steam caught his right forearm.
Pain—sharp, white, and fully real—seared through his nervous system. The outer layers of skin on his forearm instantly blistered. That turned from soot-grey to raw, weeping crimson as the tissue flash-boiled.
He bit his tongue until blood filled his mouth. He refused to scream. He refused to let his grip slip from the crowbar until he scrambled backward out of the drainage ditch.
There was no rollback here. No undo command. The burn was real, third-degree, and throbbing with painful heat that made his vision swim in grey static.
He collapsed against the cold iron of an empty coal wagon. He grabbed his right wrist to his chest, his breath coming in ragged, shallow sobs.
Across the hall, the fire gave a long, shuddering sigh.
With forty tons of heavy molten melted rock waste dumped into the sand trench, the deep water pressure inside the vessel collapsed from 3.5 MPa down to a safe, steady 0.8 MPa.
The angry crimson glow on the dark rock blocks began to fade back to dull plum, and the terrifying metal screeching of the iron hoops died away into silence.
The vessel had held.
Overseer Fang slowly crept out from behind the heavy blast door, his jaw hanging slack, his eyes fixed on the steaming trench of liquid melted rock waste.
He looked at the steadied fire. Then he looked at the starved slave slumped against the coal wagon, whose right forearm was stripped of skin and weeping serous fluid into the dust.
Fang swallowed hard, his throat dry.
“You... You stopped it,” Fang whispered, genuine shock stripping the usual cruelty from his tone.
Lin Ke leaned his head back against the cold iron wagon.
Every heartbeat sent a violent throb of agony through his scorched forearm, but through the pain, his ears caught a different sound.
A dull, wet hiss from inside the fire belly.
Lin Ke dragged his eyes open.
The sudden venting had released the internal pressure. But it had also dropped the heat inside the crucible by four hundred degrees in less than two minutes.
The leftover molten iron inside Crucible Nine was not glowing white anymore. It was turning a sluggish, muddy orange.
On the cooling walls of the vessel, the metal was already beginning to freeze.
“Fang,” Lin Ke rasped, his voice raw from steam.
The overseer looked over, his eyes wide.
“The iron is freezing,” Lin Ke said quietly. “If the crucible cools below eleven hundred degrees, five hundred pounds of grade-three spirit iron will solidify into a dead block. It will take your men three months with cold chisels to cut it out.”
Fang’s face went pasty white.
The relief on his greasy features vanished, replaced by cold, pure terror.
Dawn was two hours away.
And Elder Wu was coming.