Pino Scalise, a young Sicilian who has just served six years in prison for robbery, settles in Milan with an uncle. He goes with a dubious friend to a dating house and discovers that his cousin Marina has been plagiarised and forced into prostitution by the gang of a local boss, Don Ciccio. He therefore decides to take action to get the girl out of the ring.
Commissioner Morani, certain that the ex-convict will return to the criminal organisation, grants him a driving licence in the hope that he will lead him into the middle of Don Ciccio's shady dealings. The latter, in fact, soon blackmails Pino, who in the meantime, through his uncle, has obtained a job as a driver for an artificial flower company, finds himself forced to drive a lorry on which Don Ciccio has forced him to load drugs. Before the load crosses the Swiss border, the police intercept it and Morani, working alongside Pino, who has now become a police informer, unmasks Don Ciccio's gang with him.