While his older brother Arnaud sulks, LoÞic, with a happy heart, plays in the snow. Suddenly, a storm of big black clouds descends on them and sucks Arnaud into the sky. LoÞic wants to seek help from the adults, but the dragon Portagne des Montagnes appears. Portagne knows how to proceed. We must pursue Captain Baboune, who has just kidnapped Arnaud on his strange flying boat. Indeed, Baboune's Black Star fuels the quarrels and grumblings of captive child sailors. To free Arnaud, LoÞic must convince the crew to mutiny.