In this sequel to At the Earth's Core, return to the world of Pellucidar-an exotic, savage land at the center of the Earth, an untamed wilderness where the sun never sets. When American explorer David Innes first discovered Pellucidar, he fell under the spell of the strange world, earning the respect of many, the undying hatred of a few, and the love of the beautiful Dian. Torn from her arms by trickery, Innes vows revenge and returns to the Inner...

In response to a radio plea from Abner Perry, a scientist who with his friend David Innes has discovered the interior world of Pellucidar at the Earth's core, Jason Gridley launches an expedition to rescue Innes from the Korsars (corsairs), the scourge of the internal seas. He enlists Tarzan, and a fabulous airship is constructed to penetrate Pellucidar via the natural polar opening connecting the outer and inner worlds. The airship is crewed primarily...

The novel relates the adventures of David Innes on his return from Lo-Har to Sari in the wake of the events of Back to the Stone Age.