When a giant stone statue on Wester Island is disturbed, the legendary monster Jiger appears and heads for Japan. Gamera tries to stop this new rival, only to be injured when Jiger lays eggs inside of him. As two boys in a submarine go on a dangerous quest inside of Gamera's body to save him, Jiger threatens the Expo '70 world's fair in Osaka.

Ballet Mécanique is a Dadaist, post-Cubist art film conceived, written, and co-directed by the artist Fernand Léger in collaboration with the filmmaker Dudley Murphy. It has a musical score by the American composer George Antheil.