Sam Rivera delivered food for a living. That was not a bad thing to do. It paid the rent, it kept the lights on, and it gave him something to do with his hands while his brain figured out what to do with the woman sleeping in the next room.

The woman's name was Elena. She was twenty-nine, from Puerto Rico, and she used to be a nurse before the stress of working twelve-hour shifts at a hospital that was always underfunded and always understaffed had driven her to the brink of a nervous breakdown. She had come to Brooklyn three years ago with a degree, a suitcase, and a brother who promised to help her find work. Her brother had disappeared after two weeks, and Elena had found work anyway—cleaning offices at night, washing dishes at a restaurant on Flatbush, anything that paid cash and didn't ask too many questions.

Sam had met her at a community center where they both volunteered to translate for Spanish-speaking patients at the free clinic. He was thirty-one, born in the Bronx to a Puerto Rican father and a Mexican mother who had left when he was six. He worked for an app called QuickBite, which meant he spent his days riding a bicycle through Brooklyn, picking up burgers and tacos and pad thai from restaurants he didn't have time to eat at, and delivering them to people who would tip him in app credits instead of dollars.

They had been sharing an apartment in Bed-Stuy for eight months. It was a second-floor walk-up with peeling paint and a radiator that clanged like a bell every time the heat came on. The bedroom was small, barely big enough for a double bed and a dresser, but it was theirs, and that was more than either of them had expected to have at their age.

Elena swallowed the pendant on a Tuesday.

Sam knew it was Tuesday because he had delivered sushi to a doctor's office in Williamsburg that morning, and the doctor's assistant had told him that Tuesday was her favorite day of the week because the sushi was freshest. Elena had been in the shower when it happened. Sam had been sitting at the small kitchen table, counting his tips from the previous night—thirteen dollars in app credits and two dollars in cash—and he had heard a small sound from the bathroom. A gulp. A cough. A silence.

He had gone to the bathroom door and knocked. "You okay in there?"

"Fine," Elena had said, but her voice had been wrong. Thicker than usual, like she was speaking through water. "I'm fine. Just... swallowed something."

"Swallowed what?"

"Nothing. Just... water."

But Sam had heard the sound. It hadn't been water. It had been something solid, something that had gone down her throat with a wet click that he could still hear if he listened carefully enough.

He had gone back to the kitchen and gone back to his tips, but the sound had stayed with him.

The changes started slowly. Elena stopped sleeping through the night. She would wake up at two or three in the morning, walk to the kitchen, open the refrigerator, and stand in front of it for twenty or thirty minutes with the light on her face, staring at nothing. When Sam asked her what she was doing, she would say, "Looking for something," and then she would close the door and go back to bed.

But Sam had seen what she was doing. He had watched her through the crack in the bedroom door, and he had seen her open the refrigerator, and he had seen her take out a package of raw chicken from the grocery store, and he had seen her eat it. Raw. Standing in front of the open refrigerator, biting into the cold raw chicken with her teeth, juice running down her chin, and she had not seemed to notice. She had just eaten it, methodically, like a machine, until the package was empty, and then she had closed the refrigerator and gone back to bed.

Sam had not said anything. He had waited until morning, when Elena would wake up and act like nothing had happened, and he would make coffee and pretend he had not seen her eating raw chicken at three in the morning.

But it got worse.

She stopped showering. She stopped brushing her teeth. She stopped talking to him except in monosyllables. She would sit on the couch for hours, staring at the wall, her eyes unfocused, her mouth slightly open. Sometimes she would make a sound—a low, almost inaudible hum—that seemed to come from somewhere deep inside her chest.

And then she started talking about the walls.

"The walls are singing," she said one evening, sitting on the couch, staring at the peeling paint.

Sam had paused in the kitchen, where he was preparing dinner—spaghetti from a can, because that was what they had. "What?"

"The walls. They're singing. Can't you hear them?"

Sam had listened. He had heard the radiator clanging. He had heard the traffic on Flatbush. He had heard a siren three blocks away. He had not heard the walls singing.

"No," he had said carefully. "I don't hear anything."

Elena had turned her head slowly and looked at him, and for a moment, her eyes had been different. Not Elena's eyes. Something else. Something that had looked at him with a mixture of pity and hunger that had made his stomach turn.

"That's the problem," she had said.

He took her to a doctor.

Dr. Patel was fifty, Indian-American, and ran a small community clinic in Bushwick that served people who couldn't afford insurance or didn't want to deal with the hospital system. He was kind, patient, and had the tired eyes of someone who had seen too many people break in too many different ways.

He saw Elena on a Thursday. Sam went with her, because Elena wouldn't go by herself—she said doctors were liars and their offices were full of lies painted white—and Sam couldn't blame her. The last time she had gone to a hospital, she had been given a prescription for Xanax and told to "take a break," which was not exactly helpful when your break had lasted three years and you were still working twelve-hour shifts cleaning offices that smelled like bleach and despair.

Dr. Patel saw Elena for twenty minutes. He asked her questions. He looked in her eyes. He checked her reflexes. He asked her to name three objects, to count backward from one hundred, to describe how she was feeling.

Then he asked Sam to wait outside.

When Sam came back in, Dr. Patel was sitting at his desk, his hands folded in front of him, his expression carefully neutral.

"Mr. Rivera," he said, "Elena is not physically ill. Her blood work is normal. Her vitals are normal. There is no sign of drugs or toxins in her system."

"Then what's wrong with her?"

Dr. Patel had sighed. "I think she's experiencing a psychotic episode. Possibly schizophrenia, possibly a stress-induced break from reality. She's been under an enormous amount of pressure for a long time, and at some point, her mind just... stopped coping."

"Can you treat her?"

"I can prescribe medication. Antipsychotics. They'll help, but they won't cure her. And she'd need to take them regularly, which means she'd need to be compliant. Given her current state, I'm not sure she's capable of compliance."

Sam had thought about Elena eating raw chicken at three in the morning. He had thought about her humming in the dark. He had thought about the way she had looked at him with eyes that were not hers.

"What happens if she doesn't take the medication?"

Dr. Patel had been quiet for a long time. "She gets worse. The psychosis deepens. She becomes less and less connected to reality, and more and more connected to whatever world her mind has built to protect herself. And eventually..."

He had not finished the sentence. He didn't need to.

Sam took the prescription from Dr. Patel. It was a small white bottle with Elena's name on it. He put it in his pocket and walked her home in silence.

That night, he put the bottle on the kitchen counter. Elena walked into the kitchen at four in the morning, opened the refrigerator, and stood in front of it for twenty minutes. When she turned around, she saw the bottle.

She picked it up, read the label, and laughed. It was a small, dry laugh, like the sound of dead leaves scraping across pavement.

"Medicine," she said. "They want to give me medicine."

"Elena, Dr. Patel thinks—"

"Dr. Patel thinks I'm crazy." She set the bottle down. "I'm not crazy, Sam. I can hear them. The walls. They're singing, and nobody else can hear them, but I can, and it's not crazy to hear something that's there. It's just..."

She trailed off. She looked at him with those dark eyes, and for a moment, Sam saw something in her face that broke his heart. Not madness. Not psychosis. Fear. Pure, unadulterated fear.

"It's just that nobody believes me," she whispered.

Sam didn't know what to say. He had no words for the thing he was seeing. He had words for crazy. He had words for stressed and broken and burnt out. He had words for the things that happened to people who worked too hard and didn't sleep enough and carried too much on their shoulders.

But he had no words for this.

So he said nothing. He went to bed. He lay next to Elena, who was staring at the ceiling, and he listened to the walls humming, and he wondered if he was going crazy too.

Over the next three weeks, Elena got worse.

She stopped leaving the apartment. She stopped eating anything from the refrigerator. She spent her days sitting on the couch, staring at the walls, humming that low, inaudible hum. At night, she would get up and walk around the apartment, touching the walls with her fingertips, her eyes closed, her lips moving as if she were reading something written in a language only she could see.

Sam continued to deliver food. He continued to come home every night to the same apartment, the same couch, the same woman who was slowly disappearing in front of his eyes. He told his friends about her, and they told him to take her to a specialist, to a hospital, to a place where they could help her.

But Sam knew what kind of place they meant. He had seen what happened in those places. He had seen men and women locked in rooms with padded walls, strapped to beds, given injections that turned them into zombies. He had seen people come out of those places different—calmer, quieter, emptier.

He wasn't going to let that happen to Elena.

But he was running out of options.

He went back to Dr. Patel.

"Is there anything else?" he asked. "Any other treatment? Any other option?"

Dr. Patel had looked at him with those tired eyes. "There's a state facility. They can admit her voluntarily, or if she's a danger to herself or others, they can hold her involuntarily for seventy-two hours and then petition for longer commitment."

"She's not a danger to anyone."

"Not yet," Dr. Patel had said carefully. "But she might be. Psychosis can make people do things they wouldn't normally do. Say things. Hurt themselves. Hurt others. It's not her fault, but it's real."

Sam had walked home in silence.

He came back that evening to find the apartment empty.

Elena was not in the bedroom. She was not in the living room. She was not in the kitchen. The front door was locked from the inside. The window was locked. The bathroom was empty.

Sam stood in the center of the apartment and felt the floor tilt beneath him.

Then he heard it. A sound from inside the wall. A low, wet, rhythmic sound, like something breathing inside the space between the plaster and the studs.

He pressed his ear to the wall. The sound was louder up close. It was not breathing. It was... chewing. Slow, methodical chewing, like an animal feeding in the dark.

He pulled back. He backed away from the wall. He walked to the front door and unlocked it and walked out into the hallway and didn't look back.

He called Dr. Patel. He called the emergency number for the state facility. He called an ambulance.

When the ambulance arrived, the paramedics went into the apartment. They found Elena sitting on the couch, staring at the wall, humming her low, inaudible hum. They asked her if she was okay. She looked at them with those dark eyes and said, "The walls are singing."

They took her to the facility.

Sam did not go with them. He stood on the sidewalk and watched the ambulance drive away, and he felt something inside him go still, like a heart that had decided to stop beating.

He walked home alone. He sat on the couch where Elena had been sitting. He pressed his ear to the wall where she had been staring.

He heard nothing.

But he knew she was right. The walls were singing. He just couldn't hear them anymore.

He sat there for a long time. Then he stood up, went to the kitchen, made himself a cup of coffee, and opened his QuickBite app. There were three deliveries waiting.

He put on his jacket and walked out the door.

Outside, Brooklyn was noisy and alive and indifferent. The subway rumbled beneath the street. People walked past him on the sidewalk, each of them carrying their own private world inside their head, their own private songs in their walls.

Sam got on his bicycle and pedaled away, delivering food to people who would tip him in app credits instead of dollars, living his life one delivery at a time, in a city that would never know that the woman he loved had disappeared into the walls.