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

(Chapter 5)

The Queen orders Gene to tell her who saved him, but he refuses; after Gene sees the kids, he tells the Queen that it was Argo; the Queen is shocked, but forms an alliance with him and orders death to Argo.

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.

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