David Innes was a captive in Pellucidar, the strange world within a world that lies under the Earth’s crust. To rescue him, Tarzan comes into that savage, prehistoric land at the head of an expedition equipped with every modern device. But Pellucidar is not like the jungles the ape-man knows. Here are saber-toothed tigers and every savage creature from the beginning of time. Here the horizon curves back on itself and the sun hangs always in the middle of the sky. And now, for the first time, Tarzan is hopelessly lost in a land teeming with unknown, gigantic killers…where even time has no meaning!