Japan's Toho Studios were clearly slumming for this crudely fashioned installment in the Godzilla franchise -- a clear indication that the series was running out of creative steam and lapsing into self-mockery. The threadbare plot involves the advanced subterranean nation of Seatopia, whose leaders plan to take over the surface world with the aid of their monster Megalon, a springy cockroach-monster with a power drill mounted on his head. To this end, they steal the robot Jet Jaguar, an Ultraman look-alike invented by the amiable Goro (Katsuhiko Sasaki), to help guide Megalon's assault. Goro manages to regain control of the robot, who is capable of enlarging himself to Godzilla-like proportions, but remains ineffectual against the big bug, particularly after the Seatopians enlist the off-world aid of Gigan, the buzzsaw-sporting bird-beast. Goro sends Jet Jaguar to fetch Godzilla, who soon puts things right... more or less. Silly effects and recycled footage abound, coupled with some seriously nutty monster battles -- the highlight of which comes when the Green One executes a massive drop-kick on Megalon. The film got its U.S. premiere in 1977 in a drastically-cut version on prime-time television, which included a bumper segment featuring John Belushi in a Godzilla suit!
by Cavett Binion synopsis