The inhabitants of Murania are the lost tribe of Mu, who went underground in the last glacial period 100,000 years ago, and now live in a fantastically advanced city 25,000 feet below the surface. They cannot now breathe the air at ground level and must wear oxygen masks. (Surface dwellers have no trouble breathing Muranian air.) The Thunder Guard emerges to the surface world from a cave with a huge rock door that swings up like a garage door. Both Muranians and Professor Beetson want to get rid of Autry, so he loses his radio contract and Radio Ranch is vacated.