Just out of prison, ex-con Ugo Piazza meets his former employer, a psychopathic gangster Rocco who enjoys sick violence and torture. Both the gangsters and the police believe Ugo has hidden $300,000 that should have gone to an American drug syndicate boss. Caliber 9 is the first part in Di Leo's "Milieu" Trilogy of poliziotteschi films. It was followed by "The Italian Connection" (1972) and "The Boss" (1973).

Ugo Piazza

Nelly Bordon

Rocco Musco

Police Commissioner

Mercuri

Don Vincenzo

L'Americano / The Mikado

Chino

Pasquale Tallarico

Nicola

Hotel Clerk

Brigadier

Alfredo Bertolon

Couriers Supervisor

2nd Courier

Bartender

Policeman

4th Courier
February 15, 1972

Ugo Piazza

Nelly Bordon

Rocco Musco

Police Commissioner

Mercuri

Don Vincenzo

L'Americano / The Mikado

Chino

Pasquale Tallarico

Nicola

Hotel Clerk

Brigadier

Alfredo Bertolon

Couriers Supervisor

2nd Courier

Bartender

Policeman

4th Courier
