Fresh graduate Xu Anran and her roommate rent a ground-floor apartment with unusually cheap rent. After moving in, a strange odor lingers in the room, the walls ooze dark red, and a puppy barks frantically at the underside of the bed. Checking old news, she discovers that a suspicious case had occurred here, and the suspect was acquitted due to insufficient key evidence. But what truly makes her spine chill is that old blueprint—there is another half in the basement sealed off by partition walls. Late at night, Jiang Yu raises a hammer and smashes it toward the wall, wall dust falls rustlingly, and the hem of a woman's dress is exposed behind it.