Chow Sing Sing faces dismissal from the Royal Hong Kong Police's Special Duties Unit when a senior officer intervenes, offering him a final opportunity. Tasked with going undercover as a student at Edinburgh High School in Hong Kong, Chow must navigate teenage life while searching for a stolen revolver belonging to the officer. As he juggles his dual identity, comedic chaos ensues, testing his skills and resolve in a mission that blends action with unexpected schoolyard antics.