In the future (about next Sunday A.D.) a mysterious planet "X" appears in the Solar System and a space ship is launched to explore it.
When the ship arrives the astronauts (a Japanese and an American!) begin to explore and are capured by Devo... uh I mean the spacemen of Planet X "cue dramatic music".
It seems that Planet X is constantly under attack by Monster Zero who just so happens to be Ghidrah and the spacemen want Godzilla and Rodan to help rid the planet of Ghidrah and they are willing to trade a cure for all the diseases on Earth for the monsters.
The silly Earth people agree failing to realise two important things... one -- if the spacemen can get Godzilla and Rodan from the Earth to Planet X why don't they just transport Ghidrah away the same way (hmm. That is just to smart huh) and two -- spacemen are all evil and not to be trusted!
Godzilla and Rodan are taken to Planet X and they start fighting Ghidrah but now Earth has no defenders and is wide open for Planet X to take over! And take over they do, using Godzilla, Rodan, and Ghidrah who are all under the control of the spacemen! How can our hapless heroes defeat three monsters and the space people?
I gave this one an extra star for the cheese. I was laughing my ass off all the way through this one.