Chan Wing Yan, a young police officer, has been sent undercover as a mole in the local mafia. Lau Kin Ming, a young mafia member, infiltrates the police force. Years later, their older counterparts, Chen Wing Yan and Inspector Lau Kin Ming, respectively, race against time to expose the mole within their midst.

casts

Tony Leung

Andy Lau Tak-Wah

Eric Tsang Chi-Wai

Anthony Wong Chau-Sang

Kelly Chen