A peril of immense gravity -- or rather a lack of gravity -- endangers the enchanted land of Xanth. The Demon Earth, who rules our own world, has mysteriously disappeared. If he stays away too long, the very fabric of the world will unravel, removing the earth's gravitational field, and, incidentally, that of Xanth as well.

It's whispered that an unknown Demon has done the deed. The only weapon that can prevail against such a cosmic being is the instrument known as the Swell Foop. And the only way to handle the Swell Foop is to locate the Six Magical Rings of Xanth.

By mere chance, six adventurers have been chosen to find the rings: Cynthia Centaur and her mate Che; Breanna of the Black Wave and her now-human fiance Justin Tree; Sim, the immortal bird who will one day know all the secrets of the universe; and Jaylin, a young human girl from the Mundane land of Hawaii.

A harrowing and hilarious escapade that ranges from Earth to Xanth to a galaxy far, far away, Swell Foop is sure to delight Piers Anthony's many fans.