The film follows a series of encounters of a group of patrolling Police Tactical Unit troopers during one night, which starts off when the patrol-team tries to help a sergeant of the District Anti-Triad Squad of the Hong Kong Police Force, Lo Sa, to retrieve his lost service-issue revolver after he was assaulted by a group of triad members. The films portrays the police officers' use of extra-legal means to achieve the results of investigations and reveals the complex relationships between criminals and police officers, the hostility amongst criminals themselves and even the rivalry among different bureaux within the Hong Kong Police Force.
According to To, the budget for the film was approximately HK$4,000,000 or about US$500,000.[1] It was shot entirely at night.[1]
While the final shootout sequence of the film takes place in Canton Road, To reportedly said that "if there was a single location where he would have wanted to stage a gunfight battle, it was Cameron Road, but he could not get permission from the police to do it". The sequence was actually shot in Ap Lei Chau.[2]
