The iron rungs were bitter cold, sucking the warmth through the palms of Lin Tao’s oiled leather gloves.
Twenty paces up the upright chase, the roar of the sky drainage water chute echoed off the polished green jade walls like an approaching thunderstorm. Lin Tao climbed with steady, rhythmic smooth speed, his boots finding the center of each rung without a sound. Beneath him, Tie Shan climbed with deliberate, powerful thrusts of his thick legs. That kept his injured left shoulder pinned close to the stone.
Eighty paces above the narrow high walkway, the upright chase ended at a narrow upkeep platform forged from star-brass grating.
Lin Tao pulled himself onto the platform, crouching low against the damp, warm stone.
Directly in front of them yawned the inside access hatch of the main drainage water chute. An arched brass channel ten feet across, lined with thick green scale and crusted with dried stone salts. A heavy, star-brass flapper gate, heavy with outward iron ribs, blocked the opening.
The gate was a clockwork check valve, engineered to allow wastewater to blast out while preventing reverse airflow and climbing hunting beasts from piercing the palace underbelly.
Every seventy-two seconds, the crushing pressure from the palace bathhouses piled up behind the valve. When the water head reached critical mass, the massive brass flapper swung open, discharging thousands of gallons of boiling, foamy drain water in a violent three-second deluge before slamming shut against its bronze seat with an ear-splitting crash.
