Star Chow (Stephen Chow) is about to be kicked out of the Royal Hong Kong Police's elite Special Duties Unit (SDU). But a senior officer decides to give him one final chance: Star must go undercover as a student at Hong Kong at the Edinburgh High School to regain the officer's revolver that is overlooking. The undercover operation is made complicated when Star has been partnered with Tat - an aging, even incompetent police officers (Ng Man-Tat). But, Star still manages to fall in love with Ms Ho (Cheung Man), the institution's guidance counselor, as well as disrupting a gang engaged in arms-dealing.