People from Earth have discovered a new satellite hidden in the shadow of Jupiter that they name "Planet X". In order to verify if it is inhabited, astronauts Glenn and Fuji are sent on an expedition on board an interplanetary rocket. When they arrive on the planet, they are captured by its people who live underground to protect themselves from the terrible destruction sown by the monster zero, best known on Earth as "Kingugidora", a three headed monster that ravages all in its path. Residents of the planet X make a proposal to the two astronauts : In exchange of a cure against cancer, they ask them to help bring monsters 01 and 02, respectively Godzilla and Rodan, to planet X from the Earth in order to rid the small satellite of Kingugidora.
Of course, they aren't able to make a such decision, all the more so because it is impossible to transport monsters through space. Glenn and Fuji fly back to Earth carrying the distress message. Back on earth, they discover that the monsters are actually present in the places indicated by the aliens. But the aliens have preceded them and, on board three flying saucers, they use their fantastic technological advances to trap Godzilla and Rodan, surrounding them with a huge bubble of protective energy.
Glenn, Fuji and Dr. Sakurai are invited onboard a flying saucer to make the trip. On planet X, they observe that its residents are able to control the two monsters using a magnetic and telepathic process. Godzilla and Rodan quickly defeat Kingugidora.
To thank them, the controller from planet X gives Dr. Sakurai a magnetic tape containing instructions to cure cancer. On board an interplanetary rocket specially constructed by the residents of planet X using their advanced technology, the two astronauts and the doctor head back to Earth carrying a new hope for the whole of humanity.
But the graciousness of residents of the planet X seems a bit suspicious to our astronauts. This suspicion is very quickly confirmed when they listen to the magnetic tape. It does not contain the famous medical cure but rather a call to submission for the people of Earth. In case of refusal, an invasion from the planet X is imminent...
Spoiler ! the end of the story is revealed below…
As the Earth Committee refuses to reply, planet X launches a massive attack. Thanks to a magnetic radiation, they use the destructive power of Godzilla, Rodan and Kingugidora to sow destruction on our planet. When all seems lost, an invention of the scientist Tetsuo Teri, Fuji's sister's fiance, allows the invasion to be slowed. The invaders are sensitive to a certain resonant wave length that make them uncombative. Thanks to this invention, scientists discover how to stop magnetic rays that control the three monsters.
The victory is complete, not only the monsters stop their slaughter, but Godzilla and Rodan resume the combat against their hereditary adversary, Kingugidora. When the invader is beaten, planet X is put under high supervision.
English correction by unkown
Many thanks to you anyway