A meteorite yields the three-headed dragon King Ghidorah on Earth, after Mothra's priestesses predicted that the King of Terror would return. The monster was said to be responsible for the death of the dinosaurs, and now, he is out to get all of Earth's children. While Mothra's powers are no match for the dragon, he is sent to the past, in the time of the dinosaurs, to battle a younger, and apparently less powerful, King Ghidorah.