The heat in the Piston-Gut was a living thing. It didn't just sit in the air; it pressed against Kaelen's lungs, smelling of scorched mineral oil and the metallic tang of overstressed brass. Massive iron columns, four stories tall, hammered upward and downward in a rhythmic, deafening thunder that shook the very marrow of his bones.
Chapter 18: The Frost in the Gears
"Elara, stay by the thermal-shielding," Kaelen shouted over the roar of the steam-pistons. "If one of these gaskets blows, the vapor will flay the skin right off you."
Elara didn't move. Her eyes were fixed on the primary articulation-joint of the Vanguard's rear-left leg. "Kael, the rhythm... it's not just a mechanical skip. It's a shiver. Like the machine is trying to pull away from something."
Kaelen unslung his heavy wrench and began to climb the iron gantry. He moved with the practiced ease of a man who had spent his life in the dark spaces of the world. He reached the main steam-manifold, a forest of copper pipes that branched out like a nervous system.
He pressed his ear to the metal.
Clack. Hiss. Chime.
Kaelen froze. That last sound didn't belong. A chime was the sound of crystal. It was the sound of the Frost-Blight.
"Impossible," he muttered, wiping sweat from his eyes. "The Vanguard is moving. The friction alone should keep the hull too hot for the Blight to take root."
He reached for a manual inspection hatch. The brass bolts were covered in a fine, white rime. Not steam-condensation, but jagged, violet-tinted frost that felt like needles against his skin. He wrenched the hatch open, and a cloud of supercooled gas erupted, nearly knocking him off the catwalk.
Inside the pipe, nestled against the high-pressure steam-valves, was a cluster of violet crystals. They weren't growing; they were anchored. Someone had bolted a containment-vial of raw Frost-Blight directly into the thermal-circulatory system.
"Sabotage," Kaelen hissed, his stomach turning. "They aren't just slowing the ship down. They're infecting it."
"Kaelen! Look up!" Elara screamed from below.
From the shadows of the upper maintenance-rig, three figures descended. They weren't soldiers, but they weren't laborers either. They wore the sleek, white thermal-suits of Lady Cassia's personal retinue, their faces obscured by opaque glass masks. One of them held a high-frequency sonic cutter—a tool meant for precision metalwork, now leveled like a weapon.
"The Grounders bring the rot with them," a voice synthesized through a mask. "If the Vanguard cannot be pure, it must be stilled. The Great Chain does not need the weak."
"You're killing your own ship!" Kaelen roared, swinging himself around a steam-pipe to avoid a beam of concentrated sound that shattered the iron railing behind him.
"We are pruning the dead wood," the saboteur replied, charging forward.
Kaelen didn't have a weapon, but he had the terrain. He knew the pressure-thresholds of every pipe in the room. As the first attacker lunged, Kaelen didn't swing his wrench at the man. He swung it at the emergency pressure-release valve of the primary Nitrogen-line.
A jet of freezing gas sprayed across the gantry. The saboteur, blinded by the fog, stumbled. Kaelen was on him in a heartbeat, using the heavy head of his wrench to shatter the man's glass mask.
Underneath was the face of a young man, barely older than Kaelen, his skin marked with the pale, sickly tattoos of the Purifier cult. He looked terrified.
"Who told you to do this?" Kaelen demanded, pinning him against the vibrating piston. "Cassia?"
The boy didn't answer. He looked past Kaelen at the violet crystals pulsing inside the steam-pipe. "It is already too late," he whispered. "The frost has tasted the Core. The Vanguard is becoming a tomb."
A violent shudder rocked the entire leviathan. The deafening rhythm of the pistons suddenly changed, turning into a discordant, grinding screech. The Vanguard lurched to the left, and Kaelen felt the sickening sensation of the massive city-ship losing its footing.
"Kael! The leg is locking!" Elara cried, her hands glowing a frantic gold as she tried to soothe the machine's thermal-shock.
"I have to purge the line!" Kaelen looked at the violet crystals. To break them would release the Blight into the room. To leave them would cause the leg to shatter under the weight of the city.
He looked at his wrench, then at his sister. "El, I need you to create a localized heat-flare. Right on the coupling. I'm going to bypass the safety-locks and vent the whole manifold into the void."
"The blowback will kill you, Kaelen!"
"Only if I'm still standing here. Now, give me everything you've got!