Tarzan at the Earth's Core is Burroughs' fourth in his series set in the interior world of Pellucidar. It is also the thirteenth in his series of books about Tarzan.In response to a radio plea from Abner Perry, Jason Gridley launches a rescue expedition. He enlists Tarzan and a fabulous airship is constructed to penetrate Pellucidar. The airship is crewed by Germans and Tarzan's Waziri warriors under their chief Muviro.Edgar Rice Burroughs was an American author, best known for his creation of the jungle hero Tarzan, "Lost worlds" and the heroic Mars adventurer John Carter.