After discovering two tiny girls a foot tall each, Nelson planned to capture the two when the natives disproved of them. The rest of the group told Nelson to let the women go. Nelson was forced to agree to it and the expedition left, agreeing that the secret of the island should remain hidden. However, Nelson returned to the island and captured the girls with some henchmen and killed some natives. The rest of the natives head to their deity, Mothra in an egg, to save the girls.
Nelson forces the two tiny girls to become an attraction to make himself rich, but the two girls use telepathy to awaken Mothra. Mothra hatches from her egg as a caterpillar and swims to Japan. Several people are aware that Nelson was holding the two girls against their will and made attempts to save the two. The two girls warned the people that because Mothra would try to save them, innocent people would be hurt. Mothra destroys a cruise ship and was immune to napalm attacks. Despite the threat of Mothra, the Rolisican Embassy ignores the connection of Mothra and the two girls and defends Nelson's property rights over the two girls.
Mothra reaches Japan and starts causing destruction to Tokyo and builds a cocoon over Tokyo Tower. Energy weapons are used against the cocoon, setting it on fire. Believing Mothra to be dead, Nelson mocks the two girls until Mothra breaks out of the cocoon as a beautiful moth. The flapping of Mothra's wings caused powerful gusts of wind, causing even more destruction. Public feeling on Nelson declines, and he is then ordered to release the girls. His greed was too great however, and he flees to Rolisca that Mothra heads too. Once there however, he becomes trapped in a car with several citizens swarming him to release the girls. Some policemen order him to surrender, but are forced to kill him when he kills a policeman. The two girls are released and using church bells and a special symbol, Mothra land at an airport to pick up the two girls.