Hurled from Earth through the depths of space by a force beyond human comprehension, Jonathan Dark is forced to pit his strength and wits against the terrors of savage jungles and plains on the Jovian moon, Callisto. As Jandar, he must fight cunning wizards and grotesque beasts of prey, to survive on this savage planet and someday find a way home.

In the merciless clutches of Zhu Kor, last of the legendary Mind Wizards of Callisto, the beautiful raven-haired jungle maiden is spirited away upon a hideous winged ghastozar. Captives of a vicious tribe that worships the evil Zhu Kor as a god, while their jungle stronghold is attacked by a rival tribe, Ylana and Tomar battle savages and predatory monsters alike ... until the Galleon of the Clouds finds them in the very jaws of doom ....