In the year 196X, two astronauts, Akira Takarada as Fuji and Gorô Naya as Glenn, are dispatched to investigate a mysterious signal from the distant surface of a newly detected world on the far side of Jupiter, a planet they come to know as Planet X. Their encounter is swift and strange: they meet the Xiliens, an advanced race that appears benevolent at first, led by a figure simply known as the Controller. The aliens invite the explorers into an underground base beneath the planet’s surface, only to unleash a terrifying surface assault by a creature they call Monster Zero, which the astronauts immediately recognize as the legendary King Ghidorah. Ghidorah’s arrival shatters the calm, leaving Planet X in a tense, underground existence as the Controller explains that Ghidorah has been attacking Earth repeatedly, forcing the Xiliens to hide and mobilize in fear.
In a moment of high-stakes diplomacy, the Controller asks for a risky exchange: he wishes to borrow Earth’s two greatest monsters—Haruo Nakajima as Godzilla and Masaki Shinohara as Rodan—to defend Planet X from Ghidorah, in return for the promised cure for cancer. The offer is extraordinary, but the threat is imminent, and the astronauts return to Earth with the message that could change the balance of power between worlds.
Back on Earth, a subplot unfurls around a quirky inventor named Akira Kubo as Tetsuo, who has devised a personal alarm that emits a piercing, head-splitting sonic wave. He sells this device to Miss Namikawa, a businesswoman played by Kumi Mizuno. Namikawa’s involvement deepens when it’s revealed that she disappears before paying him, tugging Fuji’s sister Haruno Fuji further into the orbit of danger and romance. Haruno Fuji is portrayed by Keiko Sawai, and she becomes entangled with Tetsuo, drawing disapproval from Fuji, who believes Tetsuo is unworthy of his sister. Tetsuo’s path grows darker as he is captured and imprisoned by Xilien spies, intensifying the sense that danger might be closer than anyone realizes.
As tensions rise, Glenn and Fuji begin to doubt the Xiliens’ motives. Their suspicions become nearly undeniable when three Xilien spacecraft arrive over Japan. The Controller demands acknowledgment and, in a dramatic escalation, uncovers the Earth monsters—Godzilla and Rodan—summoning them through advanced technology and transporting3 Earth’s two astronauts and Sakurai, the Earth scientist, to Planet X for a tense stand-off. The stage is set for a confrontation: Earth’s monsters, aided by the Earth duo, push Ghidorah back in a fierce clash. Yet in a bid to assert control, the Xiliens manipulate the battlefield, and the trio of humans become captives under their regime.
While the rest of the crew is under the aliens’ spell, Glenn and Fuji stumble into a crisis of loyalty and fear. They encounter two Xilien women who resemble Miss Namikawa, heightening the sense of intrigue and danger around Namikawa’s betrayal and the possibility of an undercover romance. The guards recapture the astronauts and bring them before the Controller, who rebukes them but does not punish them beyond the incident. A crucial note slips into Glenn’s pocket—the message hidden by Namikawa.
Namikawa’s note is more than romance; it reveals a critical vulnerability: the sound from Tetsuo’s sonic alarm disrupts the Xiliens’ electronics. While Namikawa dies at the hands of a ruthless commander for her emotional defiance, she ensures the note reaches Glenn, lending a route to escape. Tetsuo, meanwhile, activates a prototype device that weakens the alien guards, allowing the pair to break free.
Back on Earth, Sakurai and Fuji work feverishly on a device capable of breaking the Xiliens’ control over the monsters. Soon, Glenn and Tetsuo arrive with the crucial understanding of the Xiliens’ weakness, and the moment the device is activated, the Xiliens’ hold on their own technology collapses. The invasion falters as the aliens, left without defenses, begin to destroy themselves in a mass exclusion of their technology. With their minds released from manipulation, Ghidorah, Godzilla, and Rodan awaken in a shared crisis of identity and purpose, and a spectacular battle erupts as all three monsters plunge off a cliff into the ocean, with Ghidorah surfacing again to vanish into space. Godzilla and Rodan survive by implication, leaving observers to wonder if they are still alive.
In the aftermath, Fuji acknowledges Tetsuo’s pivotal role in the victory, recognizing that the inventor’s courage and ingenuity saved Earth. Sakurai notes a desire to send Glenn and Fuji back to Planet X to study the planet more thoroughly, a plan the two astronauts accept with a sense of relief and stubborn optimism. They find a new balance in the aftermath of their harrowing experiences: Earth is safe for now, and the breakthrough that could change humanity’s future lies just within reach.
- Godzilla is brought into the narrative as a pivotal defender, portrayed by Haruo Nakajima.
- Rodan appears as a counterpart monster, brought to life by Masaki Shinohara.
- Ghidorah, the fearsome three-headed king of the skies, is embodied by Shōichi Hirose, whose presence anchors the climactic conflict between the Earth and Planet X forces.
- The Controller of Planet X is connected verbally to the actor Yoshio Tsuchiya, whose role deepens the alien machinations behind the scenes.
This tale threads political intrigue, alien manipulation, and a high-stakes race to save Earth, weaving together human grit, scientific curiosity, and a shared resolve to protect the world from threats both terrestrial and extraterrestrial.
