Mario, the head of the Mafia in France, has just been fatally injured. His "companion" decides to find a successor for him, before the New York "organization" designates one. She charges her two bodyguards to take anyone, loving money, not having any, and above all not wanting to work too much, in short, "the average Frenchman" - They discover Léon Bonnet, representing in "magic crosses". They send him gifts: champagne, weapons (a mistake ...), a ring for his fiancee, a meal worthy of the finest gourmets. In return for what, they take him to the bedside of dying Mario, and have him sign the succession. It is then that Leon, under his angelic airs, will restore order within the Mafia, by surprising all his opponents by his manners, and bypassing the police.