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

The Baxters find Gene in time to save him; Argo orders the death of all surface people; battling, Gene arrives at where the Queen is being executed, but is knocked into the path of death-dealing rays.

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

In Murania, Lord Argo is planning a revolution while on the surface, Gene flees from the Sheriff in a car without brakes.

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.