At one o'clock in the morning, Lin Wan received an invitation from his alma mater. But the alma mater was demolished three years ago. Open the door, and the rules are posted on the wall: leave before 8:50. The roommate who has been dead for three years suddenly appears: "Don't open that letter!" There are forty-seven people trapped in this building, and she may not be a human at all - someone must stay forever.
This story is so fascinating