1994 film by Stephen Chow, Lee Lik-chi

Chan Wing Yan, a young police officer, has been sent undercover as a mole in the local mafia. Lau Kin Ming, a young mafia member, infiltrates the police force. Years later, their older counterparts, Chen Wing Yan and Inspector Lau Kin Ming, respectively, race against time to expose the mole within their midst.

1991 film by Gordon Chan

A restauranteur teams up with a police officer and his ex-con brother to avenge the death of a friend's daughter.

2017 film by Herman Yau