After their life-or-death struggle on the world of "The Moon Maid," Abby Tyler and Ethan Bradley are pursued through a dimensional portal to the prehistoric land of Pellucidar. But hot on their heels are a band of Va-gas, the savage, cannibalistic, half-horse/half-human creatures from the moon, who want nothing more than to feast upon their flesh! Joining forces with Dian the Beautiful and the warrior Tanar, Abby and Ethan might just survive... But will any of them live when friends and foes alike come under attack by the hideous Horibs, the half-human/half-lizard denizens of the savage world at the Earth's core? The incredible four-part "Fear on Four Worlds" storyline that joins together Edgar Rice Burroughs' greatest sci-fi worlds of adventure continues!