Tintin is sent to guard Professor Calculus, who has invented a machine that can duplicate anything, and is staying in a village near the border of Syldavia and Bodouria. Rastapopoulous, an infamous and ruthless international criminal, tries to lure Calculus and Tintin away by kidnapping two children, who live nearby, in order to get his clutches on the machine.

Le baron de Munchausen a coutume de réunir ses amis autour d'un dîner dans son château. Il leur raconte ses fabuleuses aventures toutes sorties de sa fértile imagination.