The rain in Brooklyn never cleaned anything. It just made the grime wetter. Jack Mulcahy knew this the way he knew the weight of the revolver in his coat pocket and the fact that he hadn't eaten since the previous afternoon.

He stood in the doorway of the abandoned warehouse on Pier 47, water dripping from the brim of his hat, watching the old man feed something into a steam boiler that shouldn't have been working at all.

"You're standing in my draft," the old man said without turning around. His face was a map of scars, a line running from forehead to jaw like a crack in porcelain.

"I'm looking for someone," Jack said. "They told me I'd find him here."

The old man finally turned. His eyes were the color of dirty water. "Everyone finds someone here. The question is whether they wanted to."

Jack reached into his coat. The old man didn't flinch. Jack pulled out a cigarette instead of the revolver and lit it with hands that weren't shaking—not anymore. The war had taken that much from him, at least.

"My name's Silas," the old man said. "You're the码头 guy. Rosa sent you."

It wasn't a question. Jack hated that. "Rosa says you can fix things."

"I fix nothing. I rearrange." Silas turned back to the boiler. The flames inside were a color Jack had never seen—something between blue and gray, like the space between stars. "What's broken?"

"A person." Jack exhaled smoke. "My fiancée. Mae. She's sick, and the doctors don't know what with, and Rosa says you know something they don't."

Silas stopped stirring. The boiler hissed. "Rosa knows a lot of things. Most of them cost more than you can pay."

"I have nothing to pay with."

"Everyone has something." Silas picked up a wrench and tapped it against the boiler three times. The hissing stopped. "I need someone to go underground. The old subway tunnels beneath the East River. There's something down there that needs feeding."

"Feeding?"

"Don't overthink it. You go down. You find a room with a light. You add fuel. That's the job."

"And Mae?"

"Will get better. Or she won't. I don't make promises."

Jack should have walked away. Three years in the trenches had taught him that free things were always the most expensive. But he thought of Mae lying in their apartment in Sunset Park, her skin gray, her breathing shallow, the doctor's vague shrug, and he said, "How much?"

Silas smiled. It was not a nice smile. "Everything."

The first descent was through a service entrance behind a closed butcher shop on Canal Street. The stairs went down six flights, which was impossible—the building was only four stories tall. Jack mentioned this. Silas said, "New York is full of rooms that shouldn't exist. You learn not to ask."

The air grew warmer as they descended. Not the warm of a basement—the warm of a living thing. The walls were damp and covered in something that looked like rust but smelled like ozone. Jack's flashlight flickered and died. Silas didn't need one.

They walked for what felt like twenty minutes through corridors that weren't on any map. Jack noticed the walls were lined with pipes—thick iron pipes, humming faintly, carrying something that made them vibrate.

"Steam?" Jack asked.

"Memory," Silas said. Then, seeing Jack's expression: "Don't worry about it. Just do what I tell you."

The room at the end was circular, its walls covered in glass cylinders arranged in concentric rings. Each cylinder contained a dark, pulsing mass—no larger than a human heart, but glowing with a faint, internal light. They were connected by thin copper wires that ran along the floor like veins.

"This is it?" Jack asked.

"This is the engine." Silas leaned against the wall, suddenly looking very old. "Built it during the war. Government project. They wanted infinite energy. What they got was something else."

"What is it?"

"A heart. Biological. They pulled it from something in the deep ocean—something that burns forever. They put it in a jar and hooked it up to a machine that feeds it... well." Silas gestured at the cylinders. "Fuel."

"Like coal?"

Silas laughed. It was a dry, broken sound. "No, kid. Not coal."

He opened a metal box on the wall and pulled out a photograph. It was faded, creased, showing a woman laughing on a beach. Silas held it for a long moment, then fed it into a slot in the wall. The photograph disappeared. A moment later, one of the hearts in the cylinders pulsed brighter.

"That's the fuel," Silas said. "Memories. Physical objects tied to memories. The heart burns them and produces heat. Energy."

Jack felt something cold move through his stomach. "You're burning people's memories."

"I'm burning mine." Silas closed the metal box. "This one's mine. That one's mine. All of them are mine. I bring things down here and the heart eats them. I forget. That's the deal."

"What's the deal?"

"I can't remember what I did during the war. Not the fighting—the other thing. The thing that keeps me up at night. So I bring it down here, the heart eats it, and I forget. For a while." He looked at Jack. "Until it grows back."

Jack stood in that room for a long time, listening to the hearts pulse. He thought of Mae. He thought of Rosa, who had brought him here with eyes that were too knowing and a smile that was too thin.

"How do I feed it?" he asked finally.

Silas handed him a key. "Every night at midnight. Open the box on the wall. Put something in. Something you remember. The heart will do the rest."

"What should I bring?"

"Something you can afford to lose."

The first thing Jack brought was a watch—his father's watch, stopped at the moment his father died. He dropped it into the slot and watched it disappear. For a moment, he felt something pull at the back of his mind, like a thread being drawn from a spool. Then nothing. He could still remember his father. He could still remember the funeral. But the watch was gone, and with it, something he couldn't name.

He came back every night for two weeks. Each time, he brought something smaller. A letter. A button from his army uniform. A ticket to a movie he'd taken Mae to. Each time, the hearts pulsed brighter. Each time, something slipped away.

On the fourteenth night, he brought a photograph of Mae. Not the one from the beach—this one was from their wedding day, two years ago, before the war, before everything. He held it for a long time. Mae's face, smiling, young, alive.

He put it in.

When he woke in his apartment the next morning, he couldn't remember why he'd gone to sleep feeling so heavy. He got up, made coffee, and went to check on Mae.

She was sitting at the kitchen table, eating toast. She looked at him and said, "You're late."

Jack stared at her. He knew he should feel relief. He couldn't remember why he hadn't felt relief.

Mae's recovery was rapid. Within a week, she was walking without support. Within two weeks, she was cooking again. Within three, she was laughing.

Jack noticed she had started asking questions about things he couldn't answer. Where did they live before the war? What was the name of the dog they'd had as children? Who had given them the wedding ring?

"I don't know," she'd say, and look frightened. "It's like... there's a hole where those memories should be."

Jack didn't tell her that he had holes too. He didn't tell her that he couldn't remember his father's face anymore. That he couldn't remember the war at all—not the fighting, not the trenches, not the things he'd seen and done. That his hands knew how to hold a gun but his mind had gone blank.

He didn't tell her because Rosa came to see him.

Rosa appeared in his doorway one evening, wearing a coat that was too thin for the weather and a smile that was too sharp. "You did it," she said. "You fed the engine."

"I fixed Mae's illness."

"You transferred it." Rosa's voice was flat, matter-of-fact. "The heart doesn't destroy memories, Jack. It moves them. Where do you think Mae's missing memories went?"

Jack felt the room tilt. "Where?"

Rosa looked at him with something that might have been pity. "Into the people who feed it. Every memory you burned, every piece of your past you dropped into that slot—it didn't disappear. It went somewhere. Into the hearts. Into the machine. Into the people who carry it."

She stepped closer. "Mae isn't cured, Jack. She's full. She's carrying everything you couldn't bear to remember. And when she's full—"

"When she's full what?"

"When she's full, someone else has to take it." She touched his arm. Her fingers were cold. "You know this. You've always known this. That's why you came here. That's why you brought the photograph."

Jack didn't remember telling Rosa about Mae. He didn't remember inviting her in. He didn't remember much of anything from the past three weeks.

"Rosa," he said slowly. "How long have you known Silas?"

She smiled. It was the same smile she'd had when she first sent him to the warehouse. "Longer than you. Longer than Mae. Longer than the heart."

She left without another word. Jack stood in his doorway and listened to Mae laughing in the kitchen, and for the first time, he noticed that the laugh sounded slightly wrong—like a recording played one generation too many.

That night, he went back to the warehouse. Silas was there, sitting beside the boiler, his face turned toward the flames.

"I need to see the engine again," Jack said.

Silas nodded. "I thought you'd come back. You always come back."

They descended through the impossible stairs. The pipes hummed. The air grew warm. And Jack realized that the warmth felt like someone else's memory of a summer he'd never lived.

The hearts pulsed when they entered the room. They pulsed faster when they saw him. And Jack understood, with a clarity that was almost peaceful, that the engine was not a machine.

It was a mouth. And it was always hungry.