This crime action movie is based on Peter Maas' best-selling book The Valachi Papers. That book, in turn, is based on prison conversations and the actual U.S. Senate testimony of Joseph Valachi, a high-ranking figure in the Mafia. The book, which tells precisely who did what to whom, when and why, electrified the nation. This film had to be made in Italy, because attempts to shoot in the U.S. were stymied by mob-arranged "accidents" and protests. The story is told in flashback as Valachi (Charles Bronson) tells a Federal agent about his activities from 1929 to 1961, when he worked for the Capo of Capos, Vito Genovese (Lino Ventura). Though his tale necessarily takes place in a number of episodes, it never fails to have lots of drama and action.
by Clarke Fountain synopsis