When David Innes and Abner Perry set out to search for mineral deposits in Perry's newly invented Mechanical Prospectro, they never dreamed of discovering the beautiful, terrifying world of Pellucidar five hundred miles beneath their feet. Cast into a country of fierce fighting men, beautiful women, and vicious beasts, David and Abner take sharply diverging paths. David and his mate, Dian the Beautiful, set out to teach Pellucidar the ways of civilization and succeed in gathering a number of primitive kingdoms into the Empire of Pellucidar. Meanwhile, Abner turns his inventive genius to the science of aeronautics, with dire results for both David and Dian. The seventh and final book in Edgar Rice Burroughs's Pellucidar series, continues the epic story with a masterful blend of action, humor, and suspense. Edgar Rice Burroughs (1875–1950) is the legendary author of dozens of novels, including , , and , the latter two available in Bison Books editions. Harry Turtledove, a winner of the Hugo Award, is the author of such novels as and , provides an introduction for this Bison Books edition.