My mother started changing in the autumn of my tenth year.

At first, the changes were small. She talked to herself in the kitchen. She left food out overnight, bowls of rice and cups of wine arranged on the table as if she was expecting a guest who never arrived.

My father noticed but said nothing. He was a merchant. He spent most of his time on the road, buying silk in the east and selling it in the west. He came home every few weeks, counted his money, gave my mother a kiss on the forehead, and left again.

He did not see what I saw.

I saw her stop sleeping.

I would wake in the middle of the night and find her standing at the window, staring out at the courtyard. Her hands pressed flat against the frame. Her breath fogging the glass in a rhythm that matched nothing.

“Mother,” I said.

She did not turn around.

“There is a fox in the courtyard,” she said.

I looked past her shoulder. The courtyard was empty. The moon was full. The stones were white. Nothing moved.

“There is no fox, Mother.”

“There is.” Her voice was flat. “You cannot see it. But it is there.”

She started going out at night.

I followed her the first time. I pulled on my shoes and crept through the dark house after her shadow. She did not go far. She walked to the edge of the courtyard, to the old well that had been dry for years, and she sat down on the stone rim.

She waited.

I crouched behind the woodpile and watched.

Nothing came. The night was quiet. The stars were out. My mother sat on the well and waited for something that did not arrive.

After an hour, she went back inside.

The next morning, she did not remember any of it.

“Did you sleep well?” I asked.

“Very well,” she said. “I do not remember dreaming.”

Her eyes were dark. The skin under them was gray. She had the look of someone who had been awake for a long time without knowing it.

A month passed. My mother grew thinner. Her cheekbones began to show. Her hands trembled when she poured tea. She laughed at things that were not funny and stared at things that were not there.

The servants began to whisper.

“Possessed,” said the cook, a woman who had been with our family since before I was born. “A fox spirit. I have seen it before. It comes at night and sits on the chest of its victim. It steals the breath. It steals the soul.”

“Can it be stopped?” I asked.

She looked at me with an expression I did not understand at the time. Pity, maybe.

“A grown man cannot stop a fox spirit,” she said. “What can a child do?”

I did not answer.

But I started watching.

I watched the courtyard at night. I watched the well. I watched the shadows that gathered in the corners where the light from the house did not reach.

I kept a knife under my pillow. A small knife. The kind my father used to open letters. I sharpened it on a stone until the edge caught the light like a thread of silver.

Two nights before the new moon, I saw it.

I woke from a dream I did not remember. The room was dark. The air was cold. My mother was not in her bed.

I slipped out of my room. The hallway was empty. The main room was empty. The kitchen was empty.

I found her at the well.

She was sitting on the stone rim. Her back was straight. Her hands were folded in her lap. Her head was tilted slightly, as if she was listening to something.

Standing beside her was a fox.

It was larger than any fox I had ever seen. The size of a large dog. Its fur was red, so deep it looked black in the moonlight. Its tail was thick and long, curling behind it like a snake.

It was not looking at my mother.

It was looking at me.

Its eyes caught the moonlight. They were yellow. Slitted. Ancient. The eyes of something that had been watching human beings for a very long time and had found us lacking.

I did not move.

The fox did not move.

My mother sat between us, unaware, her breath coming slow and even, her hands folded in her lap like a doll waiting to be put away.

Then the fox turned and walked into the darkness.

My mother stood up. She walked back to the house. She passed me without seeing me. Her eyes were open but empty.

I followed her inside.

I did not sleep that night. I sat on my bed with the knife in my hand and watched the window.

The next day, I made my plan.

I went to the market. I bought a length of rope and a small jar of oil and a piece of dried meat. I wrapped them in cloth and hid them under my bed.

That night, I did not go to sleep.

I sat in the corner of the main room, in the shadow of the cabinet, and I waited.

My mother came out at the same hour. She walked through the main room without seeing me. The front door opened. She stepped into the courtyard.

I followed.

She went to the well. She sat down. She waited.

I circled around the edge of the courtyard, keeping to the shadows. I had the knife in my belt. I had the rope over my shoulder. I had the oil and the meat in a pouch at my waist.

The fox did not come.

I waited. The moon moved across the sky. The cold seeped through my clothes. My fingers grew numb.

Then I heard it.

A rustling. From the direction of the well. Not the sound of an animal moving through the grass. The sound of something coming from underground.

I crept closer.

The well.

I looked down into the darkness.

Two yellow eyes looked back up at me.

The fox was in the well. It had been there the whole time. Not in the water—the well was dry. It had made a den in the stone, a tunnel leading somewhere beneath the courtyard.

I did not hesitate.

I poured the oil into the well. I heard it splash against the stone. I heard the fox hiss.

I lit a piece of cloth and dropped it in.

The oil caught. The flame spread. The well filled with orange light.

The fox screamed.

It was not the sound of an animal in pain. It was something else. A high, thin wail that seemed to come from everywhere at once. The sound of a creature that had lived for centuries and had never expected to be hurt by a child.

The fox burst from the well.

It was on fire. Its fur blazed. It ran across the courtyard, trailing flames, leaving scorch marks on the stone. It ran toward the wall. It leaped.

I threw the knife.

I did not aim. I did not know how to aim. I threw it the way I threw stones at birds, with force and hope and nothing else.

The blade caught the fox in the tail.

It cut through. The tail fell. The fox vanished over the wall, trailing flame and blood.

I stood in the courtyard. The tail lay on the stones, still burning. I stamped out the flames. I picked it up.

It was warm. The fur was soft. The bone inside was thin and brittle.

I carried it to the main room. I laid it on the table.

My mother was standing in the doorway. Her face was pale. Her eyes were clear.

“What happened?” she asked.

“You are going to be all right,” I said.

She looked at the tail on the table. She looked at the blood on my hands. She looked at me.

I was ten years old. I was covered in soot and oil and the blood of a fox that had been haunting her for months.

“I followed the fox,” I said. “It was living in the well. I burned it. It ran away.”

She sat down slowly. She touched the tail with one finger.

“The fox,” she said.

“It will not come back.”

She started to cry. Not loud. Soft. The tears ran down her face and she did not wipe them away.

I did not know what to do. I was ten. I had killed a fox. I had saved my mother. I did not know how to comfort her.

I sat down beside her. I put my hand on the table next to hers.

She covered it with her own.

I kept the tail.

I wrapped it in cloth and hid it in my room. I did not know why. Something told me it was not over.

The next night, I heard scratching at my window.

I did not open the curtain. I sat in my bed with the knife in my hand and watched the shadow move back and forth across the glass.

The scratching stopped.

A voice came from outside. Thin. High. Like wind through a crack in the wall.

“You took my tail, boy.”

I did not answer.

“I want it back.”

I held the knife tighter.

“I will give you three days,” the voice said. “Then I will come for it. And I will take something of yours in return.”

Silence.

I waited until dawn. I did not sleep.

On the second day, I tracked the fox’s blood trail to the edge of the village. It led to an old temple, half-collapsed, overgrown with weeds. The stones were blackened. The roof was gone.

I found the den inside.

The fox was there. It had been burned badly. Its fur was patchy. Its skin was raw in places. It lay on a bed of dry leaves, breathing in shallow gasps.

It opened its eyes when I entered.

“You came,” it said.

“I want my mother back.”

“Your mother was never mine to take.” The fox’s voice was weak. “I only borrowed her. I would have returned her when I was done.”

“When you were done feeding on her?”

The fox said nothing.

I raised the knife.

“You cannot kill me,” it said. “I am older than this village. Older than the trees. Older than the road you walked to find me.”

“I am ten years old,” I said. “I do not know what old means.”

I brought the knife down.

I do not remember what happened next. I remember the fox’s eyes. I remember the sound of the blade meeting bone. I remember the warmth of blood on my hands.

I remember walking home in the dark, the tail in my pocket, the knife in my belt.

My mother was waiting at the door.

“You are bleeding,” she said.

“It is not mine.”

She did not ask whose it was.

She took me inside. She washed my hands. She made me tea. She sat with me until the sun came up.

She never mentioned the fox again.

She started sleeping through the night. She started eating. The color returned to her face. She laughed at things that were actually funny.

My father came home and noticed nothing.

I am not angry at him for that. He was a merchant. He spent his life looking at ledgers and counting coins. He did not know how to look at the things that mattered.

I am grown now. I have children of my own. I have told them this story. They do not believe me.

But I still have the tail.

I keep it in a box under my bed. The fur has faded. The bone has crumbled. It is just a piece of dead flesh now.

But sometimes, late at night, I hear scratching at my window.

I do not open the curtain.

I sit in my bed and watch the shadow move back and forth across the glass, and I hold the knife I have kept since I was ten years old.

It is still sharp.