Chen Wing Yan, a policeman, successfully infiltrates a gang while Lau Kin Ming, a tried member, becomes a mole in the police force. However, things change when both of them must seek each other out.
Director
Andrew Lau
Alan Mak
Writers
Alan Mak
Felix Chong
Cast
Andy Lau as Senior Inspector Lau Kin-ming (劉健明), Hon's mole in the Hong Kong Police Force.
Edison Chen as young Lau Kin-ming
Tony Leung as Chan Wing-yan (陳永仁), an undercover cop in Hon's triad.
Shawn Yue as young Chan Wing-yan
Anthony Wong as Superintendent Wong Chi-shing (黃志誠), Chan's superior.
Eric Tsang as Hon Sam (韓琛), the triad boss.
Chapman To as "Silly" Keung (傻強), Hon's henchman.
Gordon Lam as Inspector B (大B; Big B), Lau's subordinate who is also a mole in the HKPF.
Sammi Cheng as Mary, Lau's fiancée.
Kelly Chen as Lee Sum-yee (李心兒), Chan's psychiatrist.
Berg Ng as Senior Inspector Cheung (張Sir), Wong's subordinate.
Wan Chi-keung as Officer Leung (梁Sir), the Chief Superintendent of the Internal Affairs department.
Dion Lam as Del Piero (迪路), Hon's henchman.
Elva Hsiao as May, Chan's ex-girlfriend.
Hui Kam-fung as Officer Yip (葉Sir), Chan's cadet school principal
