A meteor strikes the ocean, awakening Godzilla and creating a storm that uncovers a giant egg on Infant Island.
In Thailand, a Japanese adventurer named Takuya is arrested for raiding an ancient temple. His ex-wife Masako visits him in jail, bringing Andoh, a representative of the Marutomo Corporation. The company offers to get Takuya out of jail if he agrees to lead an expedition to Infant Island.
When Masako, Takuya, and Andoh arrive on Infant Island, they discover the egg and two tiny twin women called the Cosmos. The Cosmos explain that they come from an ancient civilization that created two monsters, Mothra and Battra. Mothra defeated Battra eons ago, but not before the creature destroyed their civilization.
Suddenly, Godzilla returns. It destroys everything in its path, including the ship carrying Mothra’s egg. But as Godzilla attacks the egg, Battra arrives. The Mothra egg hatches, and a third creature joins the battle. In the end, an underwater volcanic eruption engulfs Battra and Godzilla.
Andoh, who fears his company will punish him for losing Mothra’s egg, steals the Cosmos. But Mothra heads for Japan to retrieve the twins and causes great destruction.
Takuya steals the Cosmos back, and his ex-wife and young daughter reunite the twins with Mothra. But the military attacks, and Mothra wraps itself in a cocoon to transform into its final form.
Godzilla returns, and Mothra hatches into a beautiful flying creature. Battra, too, transforms into a flying insect, and the two battle anew.
But when Godzilla attacks, Battra and Mothra unite to defeat it. In the end, Godzilla is sent to the depths of the ocean, but only after it kills Battra. Now Mothra must leave Earth to fulfill Battra’s destiny.
Monsters on Screen
モスラ（幼虫） Mothra Larva
バトラ（幼虫） Battra Larva
Weapons in screen
- Takao Okawara
- Kazuki Omori
- Executive Producer
- Tomoyuki Tanaka
- Shogo Tomiyama
- Tetsuya Bessho
- Akira Ifukube
- Special Effects
- Koichi Kawakita
- Release Date in Japan