Shipwreck survivors are found on Beiru Island, which was previously used for atomic tests. The interior is amazingly free of radiation effects, and they believe that they were protected by a special juice that was given to them by the island's residents. A joint expedition of scientists explores Beiru and discovers many curious things, including two women only one foot high. Unscrupulous expedition leader Clark Nelson abducts the women and puts them in a vaudeville show. But their sweet singing contains a telepathic cry for help to Mothra, a gigantic moth that is worshipped as a deity by the island people. The giant monster heeds the call of the women and heads to Tokyo, wreaking destruction in its path.