San Francisco is threatened as a bizarre, quadrapedal multi-colored subterranean monster appears underneath the city. The creature is called the Eartheater, since it lives by devouring huge amounts of rock, soil, and steel, wreaking much havoc in the process by causing buildings and other man-made structures to collapse; the Eartheater also projects waves of sonic force from two antennae on top of its head to help it dig, but which can also be utilized as a formidable weapon in battle. As the crew of the Calico travel into the underground tunnels created by the Eartheater to investigate, they're trapped by the creature. Calling on Godzilla for assistance, the Big G rescues the Calico crew and drives the Eartheater above ground during the ensuing battle. As the earth-devouring monster climbs the Golden Gate Bridge to escape, Godzilla knocks the creature off of the structure with his laser beams. Landing in the water, the Eartheater discovers his fatal weakness as he dissolves into mu