Hidden World

Also known as In Caverns Below.

A cliff overlooking tremendous galleries and caverns and far below, two armies battling with powerful destructive weapons... this was the place into which Comstock and Clay had been thrust by what they thought was an earthquake. Here, below the desert — below the silver mine which the two had been exploring — were two hidden civilizations, deadly enemies, and the possessors of far-advanced scientific secrets.

Separated from his companion, Frank Comstock found himself captured by chalk-faced people and brought into a civilization that was both bewildering and awe-inspiring. For while the people of this Alice-in-Wonderland of Wu appeared to be scientific geniuses, they looked and acted like madmen!