An hour long best of compilation of Gamera from series director Noriaki Yuasa.

As alien invaders plot to conquer the Earth, two Boy Scouts steal a mini-submarine and discover Gamera in their midst. Transported to the alien's spaceship, the Scouts are menaced by the evil inhabitants, including Viras, a squid-like monster that grows to colossal size to battle Gamera.

The film consists of re-edited material from the original television series Ultraman. Episodes 1, 8, 26, and 27 were used for the film. They were narrated by Hikari Urano as an "Ultraman Documentary". Allegedly only one new scene was shot, and that some parts of the movie where shot in black and white for unknown reasons. The movie screened at the same time as the Toho movie King Kong Escapes.

Unusual volcanic activity in Japan awakens Gyaos, a bloodthirsty flying monster with the power to slice things in half with an ultrasonic ray. While scientists and the military scramble to devise a way to stop this new threat, a young boy forms an alliance with Gamera; a monster no one else seems to trust.

Gamera escapes from his rocket enclosure and makes his way back to Earth as a giant opal from New Guinea is brought back to Japan. The opal is discovered to have been an egg that births a new monster called Barugon. The creature attacks the city of Osaka by emitting a destructive rainbow ray from his back, along with a freezing spray capable of incapacitating Gamera.