The rape and murder suspect dies in the interrogation room due to being beaten up by the crowd earlier. The three teams responsible for this case are also imprisoned together, while the other suspect is still at large. After being released from prison, the three teams, led by their captain Cheng, track down their whereabouts. They pursue the culprit for twelve years.

A haunting serial killer case from 1988 resurfaces, forcing a determined police captain to confront a dark past and solve a new wave of brutal murders in Ningjiang.