The Thompsons are trying to solve a rash of pockets being picked and Tintin decides to buy on impulse a model of an old galliard ship. But suddenly two other gentleman want to buy the model from Tintin, who refuses because he intends the model to be a gift to his friend, Captain Haddock. Then Tintin finds a small piece of parchment that was hidden in one of the masts talking about a treasure and a ship called the Unicorn. The mystery deepens when it turns out that Sir Francis Haddock, an ancestor of Tintin's good friend, was the captain of the Unicorn. After the captain tells the exciting story of Sir Francis and his glorious victory over the dreaded Barbary buccaneers, Tintin races off to track down the final pieces of the puzzle that will tell where the treasure of the Unicorn can be found.
