Journalist Steve Martin travels to Japan where he encounters something unusual in the Pacific Ocean while accompanying paleontologist Dr. Kyohei Yamane and his daughter Emiko to a remote island. They discover a relic from the Jurassic Period, a monster that has become even more dangerous due to nuclear contamination. Emiko is aware of the only way to destroy the beast as her scientist fiancé Dr. Serizawa has invented a death ray.