Capt. Vallo (Burt Lancaster), the leader of a roving band of pirates, hijacks a ship filled with expensive cargo. When a crew member (Leslie Bradley) tells him the ship was bound for an island whose inhabitants have risen up against the king, Vallo hatches a scheme to sell guns to the rebels and take their leader in for a reward. But once Vallo and his lieutenant, Ojo (Nick Cravat), are on the island, their plans change when they meet Consuelo (Eva Bartok) and the other resistance fighters.