The tunnel did not smell of death. It smelled of digestion.
Kaelen Vance froze, her hand pressed against the slime-slicked brickwork. The service tunnel was narrow, a claustrophobic intestine of the city that dripped condensation onto her neck. Ahead of them, in the suffocating gloom, the two red eyes she had spotted didn't blink. They widened.
Tick. Tick. Tick.
The sound of claws on stone grew louder, accompanied by a wet, heaving rasp.
"Don't move," Valerius whispered behind her. His voice was barely a breath, stripped of the commanding bark he used in the Cathedral. "And for the love of the Architects, Vance, do not project your hunger."
"It's a doorman," Kae murmured, her own voice vibrating with the residual energy of the gravity magic she had swallowed. "It's guarding the way down."
"It is a Midden-Dredge," Valerius corrected, his tone shifting from fear to clinical analysis. "An alchemical mistake. The Guilds used to flush failed biological experiments down here. They feed on the Dreg runoff. They are blind, Vance. They hunt by thermal vibration."
The creature stepped into the faint bioluminescent glow of the moss lining the walls. It was a nightmare of chitin and repurposed flesh—a crab-like construct the size of a carriage, but its shell was encrusted with rusted pipes and broken cobblestones. Its "eyes" were actually alchemical sensors, glowing with a dull, predatory ruby light.
It's ugly, the Voice in Kae's head noted, sounding bored. But it has a very loud mind. Primitive. Wanting. Eat it.
Kae felt the urge ripple through her—the reflex to open the psychic jaw and swallow the beast's consciousness. But she held it back. She was already overflowing with the toxic Dreg she had inhaled on the rooftops. Her veins were burning black lines up her neck. One more bite might not make her strong; it might detonate her.
"I can't sink it," Kae whispered. "I'm full."
"Good," Valerius said. He moved past her, pressing his back against the wet wall. He didn't have his shotgun. He didn't have his sword. He looked battered, his Inquisitor's coat sodden and stained with river muck, but his eyes were sharp, calculating. "If you sink it, the psychic backlash will collapse this tunnel and bury us. We have to kill it the old-fashioned way."
The Dredge chittered, its mandibles clicking together like wet stones. It sensed their heat. It lunged.
The speed was terrifying for something so large. A pincer made of serrated rusted iron smashed into the wall where Kae had been standing a second before. She scrambled backward into the muck, the impact shaking the teeth in her skull.
"The acid," Valerius snapped. "Vance, give me the canister!"
Kae fumbled at her belt, her fingers numb from the freezing river water. She threw the small metal cylinder to him.
Valerius caught it out of the air. He didn't throw it at the beast. Instead, he threw it upward.
The canister struck an overhead steam pipe—a high-pressure vent running along the tunnel ceiling. Valerius pulled a small throwing knife from his boot and hurled it with a precise, violent flick of his wrist.
The blade pierced the canister mid-air, pinning it against the hot iron of the pipe.
"Cover your ears!" Valerius tackled Kae, driving her face into the mud.
The acid inside the canister burst, eating instantly through the weakened metal of the steam pipe. The pipe ruptured.
SCREEEEEEEE.
A jet of superheated steam exploded downward, screaming like a dying banshee. The noise was deafening in the confined space. The Midden-Dredge shrieked in confusion, its thermal sensors blinded by the sudden wall of heat and white noise. It thrashed wildly, attacking the steam, its pincers shearing through stone and iron in a blind panic.
"Move!" Valerius hauled Kae up. "While it's deaf!"
They sprinted past the thrashing behemoth, ducking under its flailing limbs. A serrated leg scraped Valerius's shoulder, tearing his coat, but he didn't slow down. They slid down a drainage chute, tumbling deeper into the earth, leaving the screaming beast behind them.
They landed in a heap on a bed of gravel, breathless and shivering.
Kae spat out grit. She looked at Valerius with new respect. He hadn't used magic. He hadn't used a holy relic. He had used physics and chemistry.
"You knew the pipe was weak," she wheezed.
"I knew the acid was hydrofluoric," Valerius replied, checking the tear in his shoulder. "And I know the Guild infrastructure hasn't been serviced in fifty years. Chaos is just variables, Vance. You control the variables, you control the outcome."
He thinks he's clever, the Voice sneered, though it sounded fainter now, dampened by the depth. He thinks math can beat a god. How quaint.
"We're getting close," Kae said, ignoring the Passenger. She stood up, wiping slime from her velvet illusion-gown, which was rapidly fading back into tatters. "The air... it tastes different here."
It didn't taste like the rot of the upper tunnels. It tasted sterile. Metallic. Like the air inside a vault that hadn't been opened in centuries.
"The Deep Cisterns," Valerius confirmed. He produced a small glow-crystal from his pocket—his last one—and shook it awake. The pale blue light revealed a massive circular tunnel, lined not with brick, but with seamless, obsidian stone. "The Foundation level."
As they walked, the architecture changed. The chaotic, organic mess of the sewers gave way to harsh, brutalist geometry. The walls were etched with protective wards, but the runes were gouged and scratched.
"He's been here," Kae said, stopping.
She pointed to the floor. There were footprints in the dust. But they weren't normal footprints. They were scorched into the stone, as if the walker's feet were burning hot.
And there was blood.
It wasn't red human blood, nor was it the black ichor of the White Queen. It was gold. Molten, sizzling gold that smoked faintly in the cool air.
"He's bleeding," Valerius noted, crouching to inspect a droplet. He didn't touch it. "This is high-concentration mana-blood. His vessel is failing."
"He's powerful," Kae said, remembering how he had turned into moths at the Spire. "He played with us at the Cathedral and the Asylum. Why is he bleeding now?"
"Because maintaining a physical form while channeling the Void requires an immense caloric cost," Valerius said, standing up. "He isn't a god, Vance. He's a man trying to hold a hurricane inside a paper bag. He's burning out. That's why he needs you."
He needs a fresh skin, the Voice whispered. A vessel that stretches. Like you.
Kae looked at the golden blood. It made the Killer seem smaller. He wasn't omnipotent; he was dying. The realization hardened something in her chest. The fear that had dogged her since Chapter 1 began to calcify into anger.
"The Cipher," Kae murmured, pressing a hand to her forehead. "The map he put in my head... it's clicking."
She closed her eyes. The darkness behind her lids wasn't empty. It was filled with lines of light, a geometric overlay that matched the tunnel ahead. The "infection" wasn't just driving her mad; it was guiding her.
"Left," Kae said, her eyes snapping open. The violet glow in her sclera pulsed. "He went left."
They followed the trail of scorched footprints and golden blood for what felt like miles. The ticking sound from the upper tunnels was gone, replaced by a low, rhythmic thrumming.
Thump-thump. Thump-thump.
It was the heartbeat of the city. Or perhaps, the thing beneath it.
Finally, the tunnel opened up into a cavern so vast the light of Valerius's crystal couldn't reach the ceiling.
They stood on a ledge overlooking a massive, subterranean lake. But the lake wasn't made of water. It was made of still, black glass—solidified darkness.
In the center of the lake stood a single, colossal structure. A Door.
It was exactly like the vision Kae had seen in the telescope, but this was physical. It was three hundred feet tall, carved from white bone that seemed to absorb the light. It had no hinges. It had no handle.
Standing at the base of the Door was the Killer.
He looked small against the scale of the architecture. He had shed his starry midnight robe and was stripped to the waist. His skin was pale, covered in moving tattoos that writhed like snakes.
He was painting the door.
He dipped his hand into a bucket—no, not a bucket. A human skull. He pulled out a handful of the golden blood and smeared it across the white bone of the door, drawing complex, spiraling sigils.
"The Seal," Valerius whispered, extinguishing his light instantly. "He's trying to corrode the metaphysical locks with his own essence."
"It's not working," Kae whispered back. She could see it with her Mindsink senses. The Door was rejecting the blood. The golden sigils hissed and evaporated as soon as he painted them.
The Killer paused. He leaned his forehead against the massive bone door. His shoulders heaved. He looked exhausted. Desperate.
"Open," he screamed.
The sound echoed across the cavern, raw and human. It wasn't the theatrical, composed voice of the mastermind they had met in the Cathedral. It was the scream of a man who had run out of time.
He turned, scanning the darkness. The mirror mask was gone. His face was visible.
Kae gasped.
It wasn't a monster's face. It wasn't a demon.
It was a face she knew. It was a face she had seen on the coins of the city, in the statues of the plazas.
"That's..." Kae started.
"Impossible," Valerius finished, his grip on her arm tightening until it hurt. "That is Lord Arcanist Sterling. The founder of the Guilds. He died sixty years ago."
"He didn't die," Kae realized, watching the figure down below. "He's been waiting."
Sterling—or the thing wearing his face—looked up at their ledge. He couldn't see them in the dark, but he smiled. A wet, red smile.
"I know you're there, Black Queen," Sterling called out. His voice carried effortlessly over the black glass lake. "And I know you brought the key."
Kae stepped forward to the edge of the precipice.
"Don't," Valerius hissed. "If you go down there, you give him exactly what he wants."
"He's bleeding out, Valerius," Kae said, staring at the golden stains on the stone. "He can't open it. He's trying to brute force a lock that requires a fingerprint. My fingerprint."
She touched her temple, where the Cipher burned cold and heavy.
"I'm not going down there to open it," Kae said, the Dreg-power buzzing in her fingertips, longing to be released. "I'm going down there to break his fingers."
Careful, the Voice warned, strangely solemn. A cornered animal bites. A cornered god eats.
Kae looked at Valerius. "Do you have any acid left?"
"No," Valerius said. He pulled the knife from his boot. It looked pitifully small against the scale of the cavern. "Just steel. And bad intentions."
"That'll have to do," Kae said.
She jumped.
She didn't use gravity magic this time to slow her fall. She let the momentum build, let the hunger expand, turning herself into a kinetic missile aimed straight at the heart of the city's oldest ghost.
As she fell, the Door seemed to pulse, responding to her presence. The massive eye she had seen in the vision didn't open, but from behind the bone wall, a sound vibrated through the rock, through the air, and into the marrow of her bones.
Someone on the other side knocked back.