Beneath the vast and trackless Sahara there lies a cavern so immense the whole nations could be swallowed up within it. There reside in the eternal subterranean glow the last of the Cro-Magnons and their rivals the Neanderthals, lost remnants of ancient surface empires, and hordes of beasts and beings from all the ages of prehistory.Into this world, Zanthodon, penetrated the soldier-of-fortune Eric Carstairs - and immediately became embroiled in tremendous adventures!Hurok the Neanderthal had learned the meaning of friendship from Carstairs and in return would lead an expedition of cavemen to the dinosaur-guarded city of Zar where Carstairs had fallen captive to a sadistic queen and her scheming advisors.