A self-taught amateur detective who learned his trade from a book finds himself caught between two gangs in Milan, trying to recover a wooden leg full of drugs. He is accompanied by an unlikely trio: a deaf secretary, an undertaker and a monkey.

Henri Salvador
Gregg

Valeria Fabrizi
Morenita

Memmo Carotenuto
Sam Pestalozzo

Aldo Giuffrè
Manone

Nino Taranto
Don Cicillo

Francis Blanche
Capitano Fornace

Dolores Palumbo
Paola
Nello Appodia
Luigi Borghese
Bobo

Pietro De Vico
Un brigadiere

Giustino Durano
Un malvivente

Ignazio Leone
Un membro della banda di Manone

Enzo Maggio
Alfonso Mathis

Romano Milani