Continuing the saga of Pellucidar, the empire located in the Earth's hollow center, Tarzan at the Earth's Core is the fourth work in this classic series. The American explorer and emperor of Pellucidar, David Innes, has been captured by the deadly Korsar pirates. Picking up on the desperate cries for help emanating from Pellucidar, Jason Gridley of Tarzana brings the message to the only person who can help, Tarzan of the Apes. Together young Gridley and Lord Greystoke travel to the exotic and strange realm within the Earth to save the imprisoned ruler. Unaccustomed to the difficulties of Pellucidar, the two struggle in its savage environment, with its eternal noon and bizarre monsters, in their quest to save Innes and the precarious rule he has established.