The conniving Dr. Who builds a robot Kong in order to retrieve a highly radioactive element for his mysterious benefactor, Madame X. When the robot proves less than reliable, the devious duo scheme to kidnap the real Kong from his remote Island home of Mondo. But interfering with their plans are the heroic trio of U.S. Cmdr. Carl Nelson, Lt. Jiro Nomura, and Kong's current crush, Lt. Susan Watson.