One-Eyed Jack, great-great-grandson of that notorious pirate, Black Jack, hijacks a battleship, but he then has to face that internationally-famous detective, Inspector Willoughby in a battle of wits. Hopping into his outboard motorboat, he puts One-Eyed Jack under arrest, but One-Eyed Jack promptly sinks him and his boat with pistol fire. One-Eyed Jack laughs, but Willoughby arrests him again from the conning tower of a submarine.