Aaron Kwok as a pretty boy / pretty useless young cop who gets caught up in a case involving violent armed robbers and thus gets assigned to Lau Ching Wan's team. Then he falls in love with a KTV singer (Fennie Yuen) but of course she turns out to be the criminal boss' (unenthusiastic) girl... et cetera.
That makes it easy to find the criminals, which is just as well as the cops don't really seem to do any police work, their idea of investigating seems to be following a suspect into a brothel and then singing badly in a karoke lounge.
The final showdown takes place in a police training area, why and how the bad guys got there isn't explained but it makes for a good action setpiece to end the film. Jackie Chan produced and his hallmarks are here : fast, imaginative action.
Its not a film for plot but a film for big guns and bigger explosions.