Set in New York City's Chinatown, the film follows NYPD detective Nick Chen (Chow Yun-Fat), who is assigned to keep peace between rival Chinese gangs. He secretly works for one of the gangs to maintain order. Things get complicated when a young, idealistic cop, Danny Wallace (Mark Wahlberg), is assigned as his partner to investigate gang activity — unaware of Chen’s underworld connections.

As Wallace digs deeper, both men are forced to confront their own sense of morality and loyalty, leading to betrayal, intense action, and explosive consequences.