Every late night in Qingshi Alley, there will be three long and two short knocks on the door. Ten years ago, Xu Zhinan's father, Xu Huaichuan, opened the door that night and disappeared from the world, leaving only an old house wrapped in fog and an old pocket watch that stopped rotating. Ten years later, the knock on the door rang again, and strange past events that had been silent for a long time resurfaced.
