The Earl of Bellomont, hoping that the notorious pirate Capt. William Kidd will lead him to his buried treasure, devises an elaborate plan to save Kidd from hanging. Bellomont then arranges for Kidd and his friend, Jerry Simpson, whose left hand has been replaced by a hook, to board the ship Indian Queen incognito as passengers bound for the West Indies. On board Bellomont's ship, The Empress , Bellomont explains to Captain Avery that he has arranged for the Indian Queen to be crewed with the dregs of the waterfront in order to induce a mutiny that will force Kidd to take over the ship and then presumably head for his treasure. The Empress will follow at a distance and, to ensure communication between the two ships, Bellomont installs his lady friend, Judith Duvall, as a passenger on Kidd’s ship to signal their positions with a lantern and, if necessary, to “persuade” Kidd to retrieve his treasure. Led by Bellomont’s henchman, Steve Castle, the crew of the Indian Queen mutinies after which Castle reveals Kidd’s identity and urges the crew to make Kidd their new captain. Although he suspects that Bellomont probably engineered the mutiny, Kidd agrees to take over and share the treasure with the crew, intending to jettison them later. After Kidd rescues Judith from an attack by Castle, he takes her to another cabin while Jerry fights Castle. Jerry uses his hook as a weapon and kills Castle. When Kidd discovers that the ship’s cargo is worthless, confirming that the voyage was simply a ploy to make him reveal the whereabouts of his treasure, he tricks the crew into landing on a remote island, then abandons them. However, Judith is still on board and after Kidd catches her signaling to The Empress , he puts her in chains and makes her his “slave,” then heads for Turtle Island where his treasure is buried. Although Judith can no longer signal the pursuing ship, Avery guesses correctly where Kidd is heading. Leaving the injured Jerry on board, Kidd and Judith land on the island where they become romantically involved. Kidd discovers that notorious pirate Blackbeard has landed on the other side of the island with a large group of pirate captains, crew and wenches. After ascertaining that Blackbeard has mistaken Kidd’s boat for Avery’s, Kidd walks into Blackbeard's camp posing as Avery and introduces Judith as his slave. At a riotous feast, Blackbeard presents his fellow captains, including Anne Bonny, who later tells Kidd that she is a former sweetheart of Avery and knows who Kidd really is. She and Kidd then form an alliance. After Judith and Kidd swim back to the ship, they discover that Bellomont and Avery have caught up with them and Kidd joins Jerry in chains while Judith appears to resume her involvement with Bellomont. Later, however, Judith frees Kidd and Jerry and they row back to the island, but are pursued and caught by Bellomont’s crew. After Bellomont tortures Kidd into revealing the treasure’s location, his men recover three chests of jewels and sovereigns. When Anne then informs Blackbeard that the treasure is about to leave the island, their crews unite to attack Bellomont. After Anne is killed during the fight, Bellomont and Avery make it back to their ship with the treasure chests but are pursued by Blackbeard. A battle rages on deck as Kidd and Jerry swim up to the ship and board secretly. Blackbeard retreats to his own ship while Avery sets sail. After Avery attacks Judith, Kidd kills him. Bellomont’s men then chase Kidd and Jerry through the ship. Although Kidd creates a diversion by exploding some gunpowder, Jerry is shot. Kidd kills Bellomont in a cutlass fight, then he and Judith escape in a rowboat leaving the fatally injured Jerry behind, at his request, to steer the ship directly into Blackbeard’s approaching ship. The resulting explosion sends both ships and the treasure to the bottom of the ocean. Kidd and Judith are rescued by a British naval vessel and, after he recounts the recent events, an admiral rewards him for freeing the seas of several pirates by granting him liberty to go anywhere in the world, except Britain, where he is officially dead. Kidd and Judith embrace.