When fantasy author Lin Carter falls through a mystical portal to the jungle moon Callisto, he embarks on a thrilling interplanetary adventure. Befriending a loyal beast called Bozo and a young warrior named Taran, Carter battles vastodons, joins the crew of a mighty sky-ship fleet, and infiltrates the lair of the sinister Mind Wizards. With new friends Jandar and Glypto, Carter strives to defeat the wizardly foe and unlock the secrets of Callisto before returning home. This suspenseful tale blends science fantasy and sword-and-sorcery for an exhilarating extraterrestrial escapade.