Aliens from a dying galaxy plan to destroy our cities and build their new home on Earth. Their weapon is Mechagodzilla, a 400-foot-tall robot armed with powerful lasers and guided missiles. Only Godzilla is mighty enough to stop the colossal machine, but when Professor Mafune joins the aliens, not even Godzilla will be able to defeat them. Mafune controls Titanosaurus, a gigantic amphibious dinosaur, through a biochemical connection with his cyborg daughter, Katsura. Godzilla is no match for Titanosaurus and Mechagodzilla together, but Interpol agents have discovered Titanosaurus' weakness, which may give Godzilla the fighting chance he needs to save the world!