Secret Police: Alex Fong hangs around gangsters, stresses out his girlfriend with his reluctance to commit and embarrasses his father (Ku Feng) when he gets into trouble. Moon Lee is his sister who’s also a cop working at the same the station of her father and she can’t stand her brother nor his lifestyle. When their father is murdered in cold blood by a hired hitman (Billy Chow), Moon Lee vows to avenge his death.