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. High adventure as only Lin Carter can tell it!