The basic premise: A retired bus driver fulfills his lifelong dream of providing an extended "voyage surprise" (the title is translated as "Mystery Tour") for unsuspecting vacationers. They soon realize, while riding in the old man's home-made bus, that he hasn't bothered to plan any kind of itinerary. As a result, they end up in completely preposterous situations, of course. Voyage surprise!
The guardian is engaged to a girl from a good family, but the intervention of a gypsy will make his heart lean. This one comes in fact to take revenge and will try to kill him.
The fictionalized life, and interpreted by himself, of the popular boxing champion Marcel Cerdan. Training sessions, matches, victories, flight to the U.S.A. where the title of world champion is disputed, form the whole subject of the film.
