Cheuk Hoi travels with his undercover agents in secrecy to Bangkok, Thailand in order to uncover a drug operation. When their operation is about to end and they planned to leave Thailand, a sudden explosion killed all his agents. To make matters worse is that his good friend Eddie Cheung is killed for unknown reasons, leaving him in charge of a female cop who is officially not yet an undercover agent. Cheng Suk Mui and Cheuk Hoi are now forced to find the undercover agents (whose identities have been erased) in order to find out why Eddie was killed.