Living in the guilt of sacrificing his informant in a previous operation, Criminal Intelligence Inspector Don Lee is wary when his superior orders him to send another informant to spy on the criminal operations of Barbarian, a vicious gangster plotting a jewelry heist. He seeks ex-convict Ghost, who agrees to work for Don despite vowing to go straight since he's desperately in need of money to repay a debt and save his sister. Ghost's driving skills help him infiltrate Barbarian's gang and earn his trust, but by feeding information to Don and hooking up with Barbarian's girlfriend Dee, Ghost is pushing himself into a tight and deadly corner...
Following his confrontation with the nefarious DOA organization, Ken (Chow Yun Fat) is looking forward to going back to enjoying his retirement. His rest is cut abruptly short when his protégé Vincent (Shawn Yue), who's now working for Interpol, asks for Ken's help in taking down the real mastermind behind DOA, Aoi. The two head to Thailand, where DOA's former chief accountant Mark (Nick Cheung) has escaped with his daughter.
By a strange twist of fate, dutiful Hong Kong policeman Dan saves the life of the leader of a violent gang of armed robbers. When they commit another crime, Dan is determined to put an end to their activities. He works with the leader, whom the gang had betrayed, to engineer a plan to wreak havoc within the gang and let the gangsters kill one another. But it becomes increasingly obvious to Dan and to his colleagues that Dan is suffering from a severe mental disorder, and Dan finds that instead of upholding the law as a righteous police officer, he has now become a fugitive wanted for murder.
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.
