Chow Sing Sing (Stephen Chow) is with the Hong Kong Police and is sent on an undercover assignment to try and retrieve his superior's gun. He becomes a student at the school where one of the students supposedly stole the gun. Also stars Cheung Man as the counselor Miss Ho and Ng Man-Tat as Chow Sing Sing's police partner and also undercover fellow (as a janitor). One of my 3 favorite HK movies of all time.