When a bomb went off unexpectedly during a police operation to disarm it, Poon Shing-Fung, a bomb disposal officer, got caught in the blast and thus lost one of his legs. Poon decided to leave the police service. Five years later, the police suspect Poon, who was found in a coma at the spot of a terrorist bombing attack, of being involved in several bombing attacks in the past two years. Poon can hardly remember his past and even his identity due to Post Traumatic Amnesia.