David Innes returns to Pellucidar in the Iron Mole with weapons, supplies, and a captive Mahar, hoping to continue the work he began in the inner world, but soon after arriving he is separated from Abner Perry and discovers that the human society he hoped to unite remains divided and vulnerable. Searching for Dian the Beautiful, David struggles through prehistoric wilderness, hostile tribes, betrayal, and warfare while attempting to bring scattered human communities together and resist the continuing power of the Mahars and their Sagoth servants. What begins as a personal quest to find Dian and his old companions gradually develops into a broader campaign to unite the peoples of Pellucidar, transforming David from an adventurer struggling to survive into a leader determined to build a new civilization in the world beneath the Earth.
