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. A terrorist expert in explosives, whose gang has been dismantled, seeks revenge. He threatens to blow up a Hong Kong tunnel with hundreds of hostages. The policeman who has already beaten him once must stop him again.