After a lengthy voyage, Capt. Bart docks his ship in a London harbor and is given a new mission by British Admiralty: capture the notorious Henry Morgan, a pirate who has been wreaking havoc throughout the Caribbean. After recruiting some former shipmates for his crew, Capt. Bart sets sail in search of the infamous buccaneer, and is joined by a beautiful female stowaway in the process.

Falsely accused by the corrupt Governor Elden of Charleston of fencing stolen pirate booty, young Davey Crandall and friend Tom Botts buy passage on the ship of local buccaneer Bloodthirsty Ben. They avoid being killed by faking a case of the pox, which causes the panicked captain and crew to desert the ship. The two find themselves alone, and when a lucky cannon shot hits a mast on a British ship, they find themselves mistaken for pirates. They sail to Tortuga, where they recruit such notorious corsairs as Henry Morgan, Captain Kidd, Anne Bonney, and Blackbeard to lay siege to Chaleston and expose the villain Elden.