The Commissioner of the Police Force has lost his gun. As a group of students have just paid a visit to police headquarters, he suspects that they are connected to the case. Special Duty Unit member, Chow Sing-sing, is assigned to handle this case. He disguises himself as a student and enrolls in the school. On the other hand, Detective Tat pretends to be a janitor so as to stay in the school and help Sing out...
