Chow Sing-Sing (Stephen Chow) is about to be disqualified from the Royal Hong Kong Police's elite Special Duties Unit (SDU) because of his complete disregard for his teammates during a drill. However, a senior officer, who has taken to Sing's youthful demeanor, instead deploys him as an undercover student into Edinburgh College to recover a stolen revolver. Sing, who turned to the Police Academy because of his dislike for schooling, struggles to fit in academically. The undercover operation is made complicated when Star is partnered with Tat—an aging, incompetent police detective (Ng Man-Tat).