Milano calibro 9 is a poliziottesco film written and directed by the Italian crime film specialist Fernando Di Leo in 1972. The film is based on a novel of the same name written by Giorgio Scerbanenco. The soundtrack for the film, Preludio Tema Variazioni e Canzona, is a collaboration album between Luis Enríquez Bacalov and the Italian progressive rock group Osanna.
Small-time gangster Ugo Piazza (Gastone Moschin) gets released from prison. He tries to convince the police, the mafia, his psychotic ex-friend Rocco (Mario Adorf) and his girlfriend Nelly Bordon (Barbara Bouchet) that he wants to go straight, but everyone believes he has $300,000 of stolen money hidden somewhere.