A summer camp in the Belgian Ardennes brings together six teenagers from different national and social origins (France, Belgium, Canada, etc.). They will live a series of fantastic adventures. A newcomer to Camp Vert, Jean-Loup, a young Parisian from a wealthy family, befriends the "Cowboy" and his friends Byloke and Lustucru. In the region, young people will meet Franz and Christian, not to mention the pretty Canadian Marion-des-Neiges. Together, the Little Vagabonds will set out to discover a lost treasure and will be involved in a series of mysterious events involving a dangerous gang of criminals who had robbed a bank in London and who hold in their power a little girl, daughter of the principal witness who recognized the thieves; they threaten to kill their prisoner if her father denounces them...