The skylight latch was rusted, fused shut by years of acidic fumes. Yang Yi didn't force it. He placed his palm against the glass. He focused on the vibration of the metal frame, finding the weak point in the crystal structure of the rust.
He tapped it. Once. Sharp and precise.
The rust crumbled. The latch clicked open.
"Rat tricks," Lin whispered, peering down into the green-lit abyss of the Alchemy Hall.
"Gravity is free."
Yang Yi slid the pane aside. He dropped a coil of rope tied to the chimney. He went first.
The descent was hot. The air inside the hall felt heavy, oily, coating the inside of his nose with the taste of crushed beetles and sulfur. He landed on a narrow catwalk overlooking the main laboratory.
Rows of bronze cauldrons bubbled below, tending to themselves with low-grade flame arrays. No alchemists. The night shift relied on automation.
Yang Yi signaled Lin. She landed beside him, light as a feather, her boots barely making a sound on the metal grate.
He closed his eyes. He didn't look; he smelled.
The wolf blood wanted meat. The rat blood wanted power. It sifted through the scents of the room. Burnt mallow. Spirit grass. Viper venom.
And something else. Acrid. Volatile.
"To the left. The storage cages."
They moved along the catwalk. Below, a cauldron hissed, spewing a jet of purple steam. A mechanical arm swept over it, stirring the mixture.
They reached the storage section. Floor-to-ceiling cages made of star-steel mesh. Inside, shelves groaned under the weight of porcelain jars and jade boxes.
A heavy padlock secured the gate.
"I can freeze the lock," Lin offered, raising a hand.
"Too loud. Metal snaps when it freezes."
Yang Yi grabbed the bars. He didn't pull. He leaned in, listening to the tumblers inside the lock with his enhanced hearing. He pulled a thin metal pick—a piece of wire from the boiler room whip—from his sash.
He worked the lock. Click. Click. Clunk.
The hasp fell open.
They slipped inside.
Lin went for the labeled jars on the eye-level shelves. Healing Salve. Qi Replenishment. Bone Knit. Standard issue for Outer Disciples.
Yang Yi went to the back. To the dusty corner labeled Disposal.
"Yang, that's slag. Failed batches."
"Failures still have potency. They just have side effects."
He picked up a black jar. The wax seal was cracked. He popped the lid. The smell of ozone and rot wafted out.
Explosive Blood Pill. 30% purity. Risk of heart rupture.
He pocketed it.
He grabbed another. Bone-Hardening Paste. Toxic to skin. Causes calcification of joints.
Perfect for a weapon coating.
He rifled through the bin, stuffing his pockets with the dangerous, the unstable, the rejected. The Dragon Token hummed, guiding his hand to the items with the highest energy density, regardless of safety ratings.
A soft hiss echoed from the floor.
Yang Yi froze. His ears swiveled, picking up the sound of liquid moving over stone.
"Lin. Don't move."
"Why?"
"Guardian."
A pool of silver liquid seeped out from under the shelving unit in the center of the cage. It didn't spread like water. It coalesced. It rose up, defying gravity, forming a thick, serpentine body.
A Mercury Serpent. An alchemical construct used to guard high-value storage.
The serpent formed a hood. It had no eyes, just a smooth, reflective surface that mirrored their terrified faces.
"It senses movement," Yang Yi whispered. "And heat."
Lin was cold. Her cultivation suppressed her body heat.
Yang Yi was a furnace. The beast blood and the boiler room exertion made him glow like a beacon to the construct.
The serpent lunged.
Yang Yi didn't dodge backward. He kicked the shelf of rejected pills.
The heavy shelf tipped. Jars shattered on the floor.
The serpent flowed around the debris, liquid and unstoppable. It struck at Yang Yi's chest, its head forming a spear point.
Yang Yi caught the strike.
He grabbed the liquid metal neck. It was heavy, cold, and toxic. The mercury tried to flow through his fingers, to seep into his pores and poison his blood.
"Eat this."
Yang Yi shoved a Explosive Blood Pill into the serpent's shapeless face.
The pill dissolved instantly in the mercury.
Reaction.
The chemical instability of the pill met the alchemical binding of the construct.
The serpent shuddered. It lost cohesion. Bubbles of gas erupted beneath its metallic skin.
BOOM.
A muffled detonation blew the serpent apart. Silver droplets splattered the cage, coating the shelves and the floor.
Yang Yi wiped a splash of mercury from his cheek. It burned, but his skin healed rapidly, the rat essence purging the heavy metal.
"Grab the Healing Salves. We're leaving."
Lin swept an armful of white jars into her sash. "You just blew up a guardian. The alarm—"
A siren began to wail. A low, magical drone that vibrated in their teeth. The bronze cauldrons below stopped bubbling. The flame arrays turned from green to red.
"Run."
They bolted from the cage.
The catwalk shook. The mechanical arms tending the cauldrons snapped upward. They weren't just stirrers. They were defense mechanisms.
A bronze claw swiped at the walkway, shearing through the railing inches from Lin's legs.
"Jump!"
Yang Yi grabbed her. They didn't go back to the skylight. Too slow.
He aimed for the waste chute in the corner—a massive pipe labeled Slag Output.
He threw her in.
He dove after her just as a jet of liquid fire erupted from a cauldron, scorching the air where they had stood.
They slid down the chute, tumbling through darkness, riding a landslide of chemical ash and broken glass.
They shot out the other end, landing in a pile of soft, gray refuse behind the Alchemy Hall.
Yang Yi groaned, sitting up. He checked his pockets. The unstable pills were intact.
Lin coughed, dusting ash from her hair. She held up three jars of high-grade Healing Salve.
"We got the loot."
Yang Yi grinned. His teeth looked white against the soot and ash covering his face.
"And we woke up the whole sector."
Lights flickered on in the dormitories nearby. Shouts echoed.
"Back to the roof," Yang Yi said, scrambling up the drainpipe. "The rat hides best when the house is burning."