The undersea kingdom of Seatopia is threatened when Japan starts atomic testing near Tokyo and they fear for the survival of their civilization. The angry Seatopians send their secret weapon Megalon to destroy Tokyo and eliminate the human race. But earth still has a chance when the sleeping Godzilla is rudely awakened It becomes a titanic tag team of apocalyptic dimensions with Godzilla and robot superhero Jet Jaguar versus Megalon and Gigan in an all-out rumble to determine earth's fate!
