The film tells the story of a pair of police brothers. The younger brother Jiancheng (played by Bosco Wong) is an undercover agent, and the older brother Jianzhong (played by Michael Tse) is a narcotics police officer. The two brothers are on each other's blacklists by the police and drug trafficking groups. As a mission to escort drug dealers begins, the two are involved and unfold a drug-trafficking story with endless twists and turns.