A singing cowboy stumbles across an ancient underground civilization beneath his ranch.

Wanting everyone off Radio Ranch, Beetson frames Gene.

After defeating the guards, Gene reaches the surface and takes Beetson's airplane; the Queen kills the engine.

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.

Gene tries to stop the radium bomb sent by the Queen to kill the riders on the surface.