Xiao Jin, a new recruit in the Special Investigation Unit, and his senior colleague, Old Li, are assigned to investigate a recent case in which a married couple were murdered.
The crime scene was sealed. The power had gone out for ten minutes around the time of the murders, and the crime was believed to have taken place during that interval. However, surveillance footage of the building's exits showed no one entering or leaving. As a result, the downstairs resident, who discovered the scene and had a history of romantic disputes with the couple, became the prime suspect.
Theme: Know and obey the law, and be independent.
