hipwreck survivors are found on Beiru, an island previously used for atomic tests. Amazingly free of radiation effects, they believe they were protected by a special juice given to them by the natives. A joint expedition of Rolithican and Japanese scientists explores Beiru and discovers many curious things, including two women only a foot high. They are taken from the island, which only awakens the giant moth that wreaks havoc on Japan.

Overview from themoviedb.org