The swindler Alexander Dupre (Jean-Paul Belmondo) is released from prison ahead of schedule for good behavior, and immediately rushes to make up for lost time during his incarceration. Posing as an Indian prince, he goes on a cruise ship with the jet set, during which he meets with dazzling beauty Pamela George Eagleton (Mirella D'Angelo), a rich lady, the wife of a diamond mines owner, who has ended up in a difficult financial situation. As an honorable man the "Prince" could not refuse to offer his assistance to the lady in need and agrees to buy her diamonds. After paying in fake bills, Alexander prepares to remove the stones from the frame and discovers that they are also fakes. "Pamela" turns out to be Sophie - a fraud, exactly like himself. The couple leaves together from the ship. The next victim of their collaboration was to become the Duke of Helmuth von Nassau (Pierre Vernier (actor)). Sophie was supposed to seduce him, and then Alexander who was to be introduced as her brother, was going to fake a suicide attempt for the reason of bankruptcy. The Duke would simply have to provide financial support for the brother of his beloved. But unexpectedly to Sophie, the Duke proposes to her and writes a check for 500,000, and the criminal plan immediately flies out of her head, and the unfortunate "suicide trier" almost loses his life. Seizing the check from Sophie and wishing all the best for the future spouses, Alexander sends out to implement a different plan. His way is to Venice.