In Chongqing, police detective Chen Weikun (Nie Yuan) investigates the murder of one Ma Xudong (Yang Yiwei), whose throat was cut with surgical precision in a theater. His suspicions land squarely on the victim’s stepson Xu Feng (Xin Peng), a young factory worker who visibly loathed his violent, abusive stepfather, and would have wanted to protect his mother – but both have a strong alibi. Then there’s a mysterious figure stalking the crime scene, wearing a surgical mask, but detective Chen cannot prove anything, and the case goes cold, until ten years later he spots a prominent surgeon, Wang Dong (Luo Jin) wearing the same mask – a coincidence which rekindles his will to solve the case. Yet it turns out that this is not a coincidence, as a series of flashbacks show that Wang Dong once knew Xu Feng.
