When a robot duplicate of King Kong named Mechani-Kong is unable to dig for the highly radioactive Element X at the North Pole, the evil Doctor Who and his sponsor, Madame Piranha (Madame X in the American version), decide to kidnap the real Kong. As an insurance policy, they kidnap Lt. Susan Miller as well as her boyfriend, Lt. Commander Jiro Nomura, and Cmdr. Carl Nelson (Kong developed a crush on Susan when she, Nomura, and Nelson visited Kong at his home on Mondo Island). Kong later escapes and heads for Tokyo. Susan and the others also escape. Who and his minions follow Kong and send out Mechani-Kong to recapture him. Susan is then grabbed by the robot and taken to the top of the Tokyo Tower, where a battle ensues between Kong and his robot duplicate.—Brian Washington