At 3:17 a.m., the bell at the front desk rang.

Zhou Mian had only just started the night shift. Her manager had given her one strange instruction: when a guest checked out, verify the date before accepting the key card. She assumed the hotel had lost money somehow. Then a woman soaked to the skin pushed a card across the counter.

A white 0 was printed on it.

“I’m checking out,” the woman said.

Zhou Mian searched the system. The hotel’s room numbers began at 101. There was no Room Zero, and no record of this guest checking in. She was about to call the manager when the woman pointed to the lower right corner of the screen. “The date.”

Today was October 22. The checkout slip in the system was dated October 23 at 3:17 a.m. The guest’s name was Zhou Mian.

She looked up sharply. The woman’s hair covered half her face, but the visible eye was identical to the one Zhou Mian saw in the mirror.

The elevator chimed behind her. Its doors stood open. No one was inside, yet wet footprints ran from its floor to the counter. Zhou Mian smelled river water. There was no river within ten kilometers of the hotel.

The woman asked softly, “Did someone call you yesterday? To tell you not to work the night shift?”

Zhou Mian’s phone was in her pocket. An unknown number had called three times the previous evening. She had let it ring because the caller ID showed her own name.

The printer started without warning and spat out a receipt. Arrival: October 22. Departure: October 23. Room charge: one night. Under payment method were four words: The next guest pays.

The woman folded the receipt and pressed it into Zhou Mian’s palm. Her hand was as cold as if she had just pulled it from the water.

“Don’t give the card to the person in the elevator,” she said, and turned toward the front door.

Only then did Zhou Mian notice a shadow inside the elevator. It stood at the very back, holding another Room Zero key card, patiently waiting for her to look up.