Maffiabossen Sam (Eric Tsang) har genom sin unga medhjälpare Ming (Andy Lau) infiltrerat Hongkongs poliskår sedan tio år för att kunna veta när de tänker slå till. Under samma tid har Yan (Tony Leung), en av polisens bästa män, arbetat under täckmantel för att infiltrera maffians imperium. Under ett misslyckat narkotikatillslag inser de båda att de har en dubbelagent i de egna leden... Infernal Affairs är den hårdkokta actionthrillern som låg till grund för Martin Scorseses The Departed. Directed by Andrew Lau and Alan Mak, Infernal Affairs (2002) is a Hong Kong undercover crime thriller starring Tony Leung Chiu-wai and Andy Lau. The film follows a police officer infiltrating a triad organization while a criminal mole secretly works inside the police force. Known for its tense identity-driven narrative and modern Hong Kong crime style, the film became an international success and inspired several remakes and sequels. Från IMDB: Chen Wing Yan, a policeman, successfully infiltrates a gang while Lau Kin Ming, a triad member, becomes a mole in the police force. However, things change when both of them must seek each other out.