Peter Blood, a young Irish physician, treats a rebel soldier wounded in battle, and he is arrested, tried for treason and sent into slavery to Barbados. He and his friend Jeremy are bought by the vicious Col. Bishop, who purchases them for his niece Arabella. Blood rallies the other slaves to rebel against their slavery; they escape and take over a Spanish galleon. Blood and his crew become pirates and the scourge of the Caribbean. England, at war with France and losing, offers him a commission in the Royal Navy if he will fight for them. Blood, who has no love for the French but even less for the English, has to decide whether it's better for he and his men to fight with the English or against them.