After suffering life changing injuries in the line of duty, bomb disposal officer Fung turns his back on the police. But when a devastating series of bombings sweep Hong Kong, the police suspect their former ally may be involved after he is found unconscious at a crime scene. Now faced with memory loss and recalling only fragments of his former life, Fung sets out to uncover the truth and find out who he really is.

Hiu-tung (Veronica Yip) is a naïve young wife who is forced to raise her child alone after her gangster husband skips town for Taiwan. Her next-door neighbor is Ching-man (Tony Leung Kar-fai), a cop still coming to terms with his partner's sudden, inexplicable suicide. Inevitably, the two begin to find solace in each other's company -- Ching-man even acting as a sort of surrogate father for her son -- and soon in each other's arms. Just as true love seems about to bloom, Hiu-tung's thuggish husband returns.