Mario Gastaldi, a lawyer with no clients and no money, agrees to be a negotiator in a deal on stolen paintings, between the boss Peseti and the engineer Farnese, who plots kidnappings unsuspectedly. After he cashed from Farnese three hundred millions of lire to deliver to Peseti, Mario lets money be robbed by four pickpockets, which he is naturally in cahoots with and which he will share out it with. Money cannot be used since it comes from a kidnapping and it was marked. The lawyer will be able to make the boss get arrested.