David Innes brought back to Pellucidar the implements that would help him carve out a prehistoric empire in that weird Stone Age land at the earth's core. With twentieth-century skill and technology he could lead the tribes of Pellucidar against the dominant race of reptilian monsters and their ape-like soldiery.

But before he can subdue the terrible and inhuman Mahars, David must embark on a desperate search for Dian the Beautiful, his empress, abducted through the treachery of Hooja the Sly One. Together, they struggle to survive in a world of evils and dangers undreamed of on the surface of the Earth.

First published in All-Story Weekly during May 1915. First collected in book form by A.C. McClurg in 1923.