Deep inside Sunset Peak, the Floor 2 Heavy Foundry roared like an artificial volcano.
The air was a hundred and forty degrees. Huge overhead fans kept the shop just cool enough to work in. Four twin-crucible blast furnaces glowed white-hot, and blue arcs snapped between their copper power coils.
Inside the crucibles, one hundred and thirty-five tons of Grade-5 Silver-Steel-Carbide armor melted into rivers of silver. The plates had come from the Demolition Giants in Vault 04. Now they would keep the mountain from burning.
On a narrow catwalk above Crucible Three, Tie Kuang gripped the tilt lever with thick leather gloves. Soot darkened his neck. His gear-shaped Golden Core turned steadily beneath his ribs.
“Pouring Crucible Three!” he shouted into his throat microphone. “Clear the ladle tracks! Stand away from the gates! If I see slag in a mold, somebody’s staying for the night cleanup shift!”
He pulled the lever.
SCREEECH-CLANG!
Molten metal poured into the channels and raced toward the preheated molds. Apprentices skimmed waste from the surface before it could enter the castings.
Nearby, a fifty-ton forging press hammered a red-hot billet. The impact shook dust from the cavern roof.
Beside the press, Austin fed a twenty-foot length of seamless silver-steel pipe into his Tier 4 Heavy Pipe Bender. A steel mandrel supported the inside of the pipe so the bend would not collapse. He lowered his face shield and eased the hydraulic lever forward.
Chk-whirrrrr.
Forty thousand pounds of force pressed the pipe around the die. The metal groaned, then curved into a clean ninety-degree bend.
Austin released the pressure and checked the curve with a contour gauge.
“Ninety degrees. No wrinkles. No thin spots.” He nodded. “That’s controlled force. Try getting that with a hammer and a prayer.”
He waved to the hoist crew.
“Deburr it, stamp it, and send this header to the surface. Use nylon slings.”
Up on the Obsidian Plaza, the air smelled of crushed rock and sweat.
Three thousand cultivators in orange vests, safety glasses, and yellow hard hats tore through the granite. In under eight hours, they cut all three thousand feet of trench.
Grand Elder Xuan Xiao stood waist-deep in the main channel with an oak tamping bar in his hands. He had tucked his white beard into his vest to keep it away from the machinery.
“Keep the gravel even!” he shouted to twenty Golden Core elders. “Check the string line every ten seconds! The general contractor wants a four-inch bedding layer with less than a sixteenth of an inch variance! If a pipe rattles under pressure, our sect’s honor dies in this ditch!”
A younger elder held up his bleeding hands. “Grand Elder, my silk wraps are soaked through! In two hundred years of cultivation, I have never suffered like this!”
“Silence!” Xuan Xiao brought his tamper down with a hollow thud. “Feel your spiritual energy! Each strike strips away illusion. We are grinding our vanity against the bones of the world! Pack that corner before the inspector comes!”
A dozen paces away, Patriarch Iron Blood worked like a full concrete crew.
He had traded his crimson robes for denim trousers, though he still wore his orange vest and hard hat. Three eight-hundred-pound concrete trench covers rested across his shoulders.
He trotted over the gravel and lowered them into place.
THUD. THUD. THUD.
Iron Blood dropped to one knee and ran a thumb across the joints.
“Flush! Dead flush! No trip hazards!” He grinned at his disciples. “If I find one pebble under these covers, I’ll grind your bones into three-quarter-inch aggregate!”
The freight hoist rose without pause, bringing beams, headers, and finned cooling coils from the foundry.
High above the plaza, Austin stood on a rolling scaffold with a pneumatic rivet gun and an ultrasonic welder.
CHUNK-CHUNK!
The gun drove silver-steel rivets through the gusset plates. The noise rattled every jaw on the summit, but Austin did not flinch. Once each rivet was set, he sealed the joint with the welder. The metal fused without warping the frame.
By the time the countdown reached forty-eight hours, Sunset Peak looked like a refinery.
Eight eighty-foot radiator towers stood around the plaza. Heavy cross-braces held their frames steady. At the top of each, six silver-steel fan blades waited inside a fifteen-foot housing.
Austin climbed down Tower 1 and crossed to its main valve. Tie Kuang and Jiang Taixu followed with clipboards.
“Static pressure held,” Austin said. “That doesn’t prove the loop works. Start the pumps at one-quarter load.”
Cold coolant entered the underground lines. Towers 1, 2, and 3 frosted evenly. Then Tower 4’s inlet gauge jumped into the red. Its return line stayed warm while the pump note climbed toward a scream.
“Shut it down!” Austin shouted.
The emergency stop came too late. A gasket split above Tower 4. Coolant burst across the scaffold, and the crew scattered as the fan motor tripped off.
PSSSSSSSSHHHH—CLANG!
Nobody was burned, but the failed gasket struck the deck hard enough to dent it.
Li Xiaoyao had been checking the trench markers below. He raised one hand, but did not touch the wet pipe.
“Master Chu, the return line rises before it drops into this trench. There’s an air pocket at the high bend. And Tower 4’s crew opened every valve because the others were cooling faster.”
Austin crouched beside the exposed bedding. The return pipe rested on a ridge of loose gravel. One inexperienced crew had laid it against the grade marks; another had overloaded the tower to make up for the weak flow.
“That’s the fault,” he said. “Bad bedding trapped air. Then they tried to fix a plumbing problem by throwing more load at it.”
Xuan Xiao and Iron Blood arrived at a run. Both looked at the damaged gasket, then at their own workers.
“I signed the trench inspection,” Xuan Xiao said. His face had gone gray. “We were racing the other crews.”
“I told Tower 4 to match the frost line,” Iron Blood admitted. “I did not ask why it was behind.”
Austin looked at the countdown. They could force a patch and hope it held through ignition. The pump was already shaking the pipe supports.
“We hold ignition,” he said. “Use the containment brake and buy twelve hours. No core startup over a broken loop.”
Tie Kuang stared at him. “Can the brake hold that long?”
“It has to. Xuan Xiao, re-bed the return line. Iron Blood, rebuild Tower 4’s valve settings and replace that gasket. Your crews made the mistakes. Your crews will find the rest and fix them.”
Austin stepped back from the open trench rather than taking the tools himself.
“I inspect the finished work. I don’t repair it for you. Learn the job now.”
The moon went out while they were still working.
It did not drift behind a cloud. The sky simply slammed shut.
The wind died. A crushing pressure settled over the summit, making ears pop and teeth ache. In the valley, every bird fell silent.
Austin looked up.
His countdown showed twenty-four hours remaining.
[CORE IGNITION COUNTDOWN: 24:00:00]
A storm front five thousand miles wide rolled over the western ridge faster than sound. Violet lightning twisted inside it, bright enough to turn night into day.