Most of the action takes place in Pellucidar, Earth's inner world, which is a vast place with oceans and continents of its own. In this strange realm, Burroughs has unleashed his imagination to run free of the natural restrictions of Earthly lands such as Africa, where the setting, conditions, and creatures need to conform to what is known about the country. Burroughs makes excellent use of this imaginative freedom to populate Pellucidar with fantastic denizens—devising new species of intelligent beings, mixing prehistoric animals with creatures of his own invention, and conjuring up exotic locales to suit the needs of his plot. For instance, when David and Dian need some time together to forge their bonds of love, nearly impassable mountains appear where they can live together isolated from the events of the rest of the world.

The "buried city of Phutra" is a fine creation inhabited by slaves, guards, and the Mahars, winged reptilian beings. The open spaces, the streets, and the interiors of buildings are well described, creating the impression of a very ancient city built to meet the demands of its masters. The temple where the queen and other Mahars feed on humans is suitably primitive yet impressive, built out of rock, with a mysterious interior. The outdoor scenes may not be quite as richly developed as the indoor ones, but the vast plains of Pellucidar teem with wildlife and make excellent terrain for battles, and the mountain home of David and...

(The entire section is 525 words.)