Pellucidar

David Innes has bored back down through five hundred miles of the Earth's crust in his great iron mole, returning to Pellucidar — the sunlit world on the planet's hollow interior, lit by a central sun that never sets, hung with a horizon that curves upward overhead, and ruled by the cold, telepathic reptilian Mahars and their brutal Sagoth soldiers.

He comes back armed with the rifles, books, and instruments of the outer world, and with one purpose above all: to find what he left behind — his friend the inventor Abner Perry, his allies among the human tribes, and above all Dian the Beautiful, the mate he won and lost. But he emerges alone on an unknown shore of a trackless, timeless world, and his treacherous enemy Hooja the Sly One has designs of his own upon Dian.

Innes has brought more than a rifle, though — he has brought an idea. With Perry's ingenuity supplying gunpowder, firearms, and at last a navy, and the loyalty of allies like Ja of Anoroc and Ghak the Hairy One, he sets out to weld the scattered, warring tribes of men into a single nation — the Empire of Pellucidar — strong enough to break the reptile masters and seize the inner world for its own kind.

First serialized in 1915 and published as a book in 1923, Pellucidar is the novel in which Burroughs truly built his hollow earth, one of the most enduring works of the lost-world tradition. It is presented here complete, to be read for what it is: swift, inventive, wholeheartedly committed, and, in places, very much a product of its time.