A kidnapped beauty gets caught between feuding pirates.

In Port Royal, Jamaica, in the early eighteenth century, Robert Maynard poses as a surgeon in order to board pirate Charles Bellamy's ship. Maynard has turned spy because Jamaica's governor suspects that Bellamy is in league with Sir Henry Morgan, a former pirate who has been assigned by the King of England to protect the seas. The governor has offered a reward to anyone who can prove that Morgan is receiving pirate loot. As soon as Maynard and fellow spy Briggs board the ship, they learn that the notorious pirate Blackbeard has murdered Bellamy and taken over as captain. Beautiful passenger Edwina Mansfield, a pirate's daughter, is furious at Blackbeard because she had planned to marry Bellamy, but Blackbeard, who wants Morgan dead, knows that the nobleman is infatuated with her and will pursue her. Blackbeard then orders Maynard to remove a bullet from his neck, and ever-suspicious, demands that sailor Gilly watch the newcomer during the operation. Unknown to Blackbeard, Gilly is in league with Maynard and slips him a note begging him to slit the pirate's throat, but Maynard declines. Later, while Blackbeard is up on deck, Maynard slips into the captain's quarters and locates Bellamy's logbook, which he hopes will contain evidence that Bellamy gave Morgan stolen goods. Before Blackbeard discovers him, Maynard manages to rip out the book's incriminating pages. Maynard then defends Edwina against the unwanted advances of a lecherous pirate, killing him with his dagger. A grateful Edwina admits to Maynard that she agreed to marry Bellamy to escape from Morgan, from whom she has stolen treasure, which is now hidden in a clothes chest. Blackbeard suspects Edwina's crime and breaks open one of her chests but discovers only letters in which Edwina implicates Morgan as Bellamy's cohort. Maynard tries to steal the letter, but Blackbeard stops him, noting that if Morgan were arrested, all of his loot would go to the King. Soon after, Blackbeard, having plied Edwina's talkative servant Alvina with liquor, finally identifies the treasure chest and claims it. Although Maynard has made plans to jump ship with Briggs, he sends Briggs on alone with the logbook pages in order to help Edwina, who fears that Morgan will force her to marry him. Maynard chops a hole in the hold, and the next morning, as the ship founders, Blackbeard, having deduced Briggs and Maynard's mission, gives the surgeon a severe beating. Blackbeard then orders the crew to abandon the ship and hide on a nearby island. That night, Blackbeard's first mate, Ben Worley, accuses the pirate of hoarding the loot. To appease Worley, Blackbeard suggests that they bury the chest together on a neighboring beach, and the two watch as Maynard and Jubal, another sailor, dig a deep hole in the sand. When their rowboat suddenly comes unmoored, Maynard and Worley race off to secure it, and during their absence, Blackbeard orders Jubal into the hole, then shoots him. Blackbeard hides the chest among some rocks and refills the hole before Maynard and Worley return. Although Worley deduces Jubal's fate, he believes the treasure is buried and suggests to Maynard they conspire to do away with Blackbeard. The next morning, Blackbeard spies Morgan and his men on the beach and attacks them with cannon fire. During the ensuing battle, Maynard frees Edwina from Blackbeard's guards, while Blackbeard tricks a crazy, bearded beachcomber into dressing in his clothes. Blackbeard then shoots the man in the back, leaving his body to be discovered by Morgan, who assumes he has killed Blackbeard. Morgan defeats the pirates, reclaims Edwina and orders Blackbeard's head chopped off for display in Port Royal. Later, in the city, Maynard learns from his uncle Jeremy that Morgan connived to have the governor arrested and has assumed his post. Fearing for his life, Maynard decides to escape on Blackbeard's ship, which Morgan is sending back to England. Under cover of darkness, Maynard sneaks in to see Edwina at Morgan's villa and persuades her to leave with him. When the couple boards the ship, however, they discover that Blackbeard and his crew of escaped convicts have claimed it. Morgan pursues in a captured Spanish galleon, but halts his assault on Blackbeard's ship as soon as he sees Edwina tied to the mast. By threatening Edwina, Blackbeard then forces Morgan to sail away. That night, Worley, fed up with the captain's greed, encourages the crew to mutiny and retrieve the buried treasure on the island beach. After some fruitless digging, they locate the chest among the rocks and drag it back to the ship. Blackbeard has anticipated the mutiny, however, and greets them with deadly gunshot. When Blackbeard tries to escape with the treasure, however, Gilly and the other sailors shoot and stab him. They then bury him in the sand up to his neck and leave him to be drowned by the rising tide. Nearby, Edwina and Maynard steal a rowboat and, once safely at sea, kiss.