: Tarzan of the Apes, Jason Gridley, and the crew of the airship O-220 return to Pellucidar, the world at the Earth's core, on a wartime mission to stop the Nazis from obtaining a powerful superweapon. But when the Lord of the Jungle's murderous adversaries partner with the Mahars-Pellucidar's routed reptilian overlords-and his adventurous granddaughter Suzanne goes missing on a reconnaissance mission, can Tarzan prevent the conquest and enslavement of all humanity in both the inner and outer worlds? Also includes the bonus novelette 'Victory Harben: Clash on Caspak' by Mike Wolfer.