When the evil alien Zanon comes to enslave Earth, all hope seems lost. The Earth's resident superheroes, the Spacewomen, are powerless to stop him. They must enlist the help of a young boy who has a special connection with the giant turtle Gamera. The Friend of All Children then battles Gyaos (a flying monster), Zigra (an alien shark), Viras (a space squid), Jiger (a giant lizard), Guiron (a space beast) and finally Barugon (another giant lizard). Gamera then sacrifices himself to kill Zanon by destroying the space pirate's ship.