Infernal Affairs

The film follows the parallel lives of Ming (Lau), a cop who secretly reports to ruthless Triad crime boss Sam (Eric Tsang); and Yan (Leung), an undercover police officer who poses as a Triad member in Sam's gang. For Yan, the years of living in the criminal underworld have taken their toll, and he longs to return to regular police duty. However, the only person who knows Yan's true identity is his mentor Superintendent Wong (Anthony Wong), also the unsuspecting superior of Ming. When Wong's officers come face to face with Sam's gang, both leaders realize there are moles in their midst. Soon Yan and Ming must track each other down, leading to an inevitable confrontation.