At midnight, young man Zhou Chen takes the last subway of Linjiang City, but unexpectedly encounters a series of unexplained abnormal events. During the train's operation, mysterious riding rules appear inside the carriage, and the familiar subway lines also change. To find a way to leave, Zhou Chen begins to observe the abnormal phenomena around him and searches for clues together with fellow passenger Xu Wei. After leaving the subway, the two discover that there are many similar abnormal areas in the city. Midnight convenience store, Hepingli residential building, Hongchuan Center Building—different locations successively exhibit inexplicable phenomena. As the investigation deepens, Zhou Chen meets food delivery rider Chen Ye.