Tintin finds himself involved in a mystery related to a drowned man, a can of crabmeat and a ship called Karaboudjan. After investigating the ship, Tintin discovers that the shipment of cans does not contain exactly crabmeat.

Tintin buys an old model ship at a flea market as a gift for Captain Haddock, who tells him about the exploits of a famous ancestor related to it. Then, Tintin learns that it is not an ordinary model ship.

Tintin and Captain Haddock search for Red Rackham's treasure with the help of an eccentric but lovable professor.