The cunning con artist Johnny Farrell is saved from death by the enigmatic Balin Mandson, the owner of a major casino. Johnny becomes his right-hand man, but the friendship between them begins to fall apart when Balin returns to town with his young wife, Gilda, after yet another absence. Everything suggests that Gilda and Johnny were once lovers, but now their feelings seem more like mutual hatred.

Schoolgirl Yana finds a giant egg in a cave, which, according to legend, is home to demons. A small monster hatches from the egg, and the girl decides to tame it. The monster grows, and with it grows the threat to both Japan and all of humanity. If the fire-breathing Gamera does not come to the world’s aid and destroy the bloodthirsty monster, a new apocalypse will ensue.