Three young pirates - Thomas, Marie and Willy - while on a nearby island, see a magician's performance for the first time. The dexterity of his hands mesmerizes the little heroes, and Willy the Smart is quite impressive. On the way home, the heroes meet an old ship in the open sea on which a girl was abandoned by pirates. Who will the stranger turn out to be, and will Willy be able to solve the magician's most important trick?