On a remote island in the Pacific, G-Force members Koji Shinjo, Kiyoshi Sato, and Major Akira Yuki discover the baby Godzilla, and strange crystalline shaped formations. Shinjo and Sato are attempting to control the King of the Monsters, while Yuki plans on killing Godzilla. Meanwhile, telepath Miki Saegusa is contacted by Mothra’s familiars, the Cosmos, who tell her a monster has arrived to kill Godzilla, and then conquer the Earth.
A Godzilla-like monster, encrusted with crystals, is heading toward Earth. A giant robot, Mogera, is dispatched to intercept the SpaceGodzilla. Miki has joined the G-Force team on the island and contacts Godzilla after a telepathic amplifier is implanted in his neck.
In the asteroid belt, SpaceGodzilla easily defeats the robot, and Mogera spins out of control. Soon thereafter, it arrives at the same South Pacific island, and is energized by the crystalline structures. It attacks little Godzilla with lightning bolts from its mouth, but now faces Godzilla’s wrath. Godzilla’s fiery breath, though, is deflected by a forcefield. Spacegodzilla takes to the air and encircles the other two monsters, blasting at Godzilla until he falls. The alien beast uses telekenetic powers to send little Godzilla into one of the structures. It flies off, leaving Godzilla to lick his wounds.
A study of cells found near the battle indicate SpaceGodzilla was created by Godzilla cells that managed to get into space, where they grew and mutated.
Yuki heads a team with Shinjo and Sato and fly a repaired Mogera into battle against Spacegodzilla who has arrived in Fukuoka. Mogera attacks the alien beast, with limited effect, ending with the robot crashing to ground. Godzilla arrives and faces off against Spacegodzilla.
The alien beast quickly renders Godzilla unconscious, lifts him in the air, and throws him into a skyscraper. Godzilla picks himself up and approaches the other beast, but Spacegodzilla is floating in the air and attacking again with lighting. Godzilla blasts at the crystalline structures, weakening his opponent. SpaceGodzilla launches the missile shaped crystals at Godzilla, to slow the approaching King of the Monsters. Godzilla’s nuclear fire is glancing off the other’s force field.
The crew of Mogera separate the Star Falcon from the rest of the robot and close in for an attack while Godzilla attempts to destroy the alien’s power source. Mogera burrows underground, as the Falcon flies into battle. Separately they manage to sneak up on SpaceGodzilla and surprise him while his forcefield is down. The Falcon docks with Mogera, and the robot and Godzilla double team against the the space monster. Godzilla and SpaceGodzilla wrestle, with Godzilla thrown off. SpaceGodzilla turns its attentions to Mogera, severely damaging it. Shinjo and Sato abandon the robot, with Yuki staying behind. With SpaceGodzilla distracted, Godzilla gathers himself up and, with renewed strength, slams into the other monster. Yuki struggles to bring the robot back into the fray, but and manages to slam into SpaceGodzilla, causing it to fall. But the robot is spent and crashes into a building.
SpaceGodzilla rises up, and continues the battle. Godzilla is emitting energy, which will cause SpaceGodzilla to explode. Yuki escapes from Mogera moments before SpaceGodzilla explodes in a massive fireball. Little Godzilla is freed from his imprisonment.
Godzilla exits the battlefield, but there are hints that there may be another space monster.
Human Cast: Jun Hashizume (Lt. Koji Shinjo), Megumi Odaka (Miki Saegusa), Akira Emoto (Major Akira Yuki) Zenkichi Yoneyama (Lt. Kiyoshi Sato)
Monster Cast: Godzilla, SpaceGodzilla, Mothra, Mogera, Little Godzilla
LogBook entry by Robert Parson