One of Hollywood's favorite scenarios--as intelligent reptiles battle stone age humans for control of an alternate Earth. Driven south by a deteriorating climate, tribes of hunter-gatherer humans come into contact with the tropic-dwelling Yilane, cold-blooded creatures whose appealing civilization is convincingly based on genetic engineering techniques. (Their cities, tools, and weapons are all modified living entities.) The two races, though, at once begin to fight out of mutual loathing and incomprehension. And, in one skirmish, the Yilane capture six-year-old hunter's son Kerrick and convey him to their newly-founded city Alpeasak. So, during a long captivity, Kerrick painfully learns to communicate with the Yilane, absorbs their advanced civilization, and wins the grudging acceptance of war leader Vainte; his human memories grow dim. Then the Yilane bring in a prisoner, the hunter Herilak, for Kerrick to interrogate: forcefully reminded of his origins, Kerrick stabs Vainte and escapes with Herilak. Vainte vengefully pursues with a hugh army; Kerrick and Herilak, joining with other tribes, find sanctuary beyond the mountains. But soon the Yilane discover their whereabouts, and Kerrick resolves to attack the Yilane city in a desperate attempt to end the threat--a conclusion that leaves plenty of scope for sequels. Despite substantial embellishments, this familiar plot is offered up in a narrative that's only sporadically gripping and exciting--and, uncharacteristically for peripatetic veteran Harrison, totally humorless. (The somber tone underlines the gloomily xenophobic message here.) Still, if you enjoyed Hubbard's Battlefield Earth, you'll certainly enjoy this professional, often-engaging recycling of tried-and-true notions.