The seemingly ordinary city was shrouded in an uneasy haze after a mysterious event three years ago - "Twilight". That incident caused amnesia for many people, including college student Xia Fan, who couldn't remember why she appeared on the edge of the incident covered in blood. Three years later, in order to trace the truth behind his amnesia and get rid of his pursuers, Xia Fan persuaded the calm and rational physics genius Xue Changjiang Shu to pretend to be her lover. However, this contractual relationship full of lies and performances involved them in a bizarre murder that occurred at a location related to the incident three years ago.
At the same time, Xia Fan's childhood sweetheart Li Yang, a police trainee with a sense of justice but a little impulsive, and Jiang Shu's ex-girlfriend Wen Yan, a psychiatric intern who has become taciturn, are also forced to interact with the two. Li Yang suspected that the murder case was related to the "Twilight" three years ago, and desperately tried to dig out the truth, but it touched the painful memories that Xia Fan was trying to forget. Wen Yanze seemed to be secretive about the past, and her avoidance confused Jiang Shu.
As the investigation deepens, the four people gradually discover that the "Twilight" three years ago was not an accident, but a huge and carefully designed conspiracy. Amnesia is a deliberate act of some kind of force. The appearance of the deceased seems to be to conceal a vital secret - a passage that cannot be closed after being opened by a "key", or an activated and uncontrollable supernatural ability. The fragmented memory fragments of each party may be a key piece of the puzzle. Lies and truth intertwine and heat up in fear, secrets and betrayal
