A singing cowboy stumbles across an ancient underground civilization beneath his ranch.
The Baxters leap to safety but are captured, and brought to Murania; Gene is unable to help, as the door control is disabled; the Baxters switch the door control, but get hit by radium rays.
After defeating the guards, Gene reaches the surface and takes Beetson's airplane; the Queen kills the engine.
Gene is pulled to safety, and the Queen is rescued; the ray goes wild, destroying Murania; the Queen orders all to the surface, where everyone and the ranch are safe, while staying behind herself.