Score, Renald, and Pixel are snatched from different worlds and taken by Bestials to the planet Treen, where they are to be offered as a sacrifice.

When Oracle suggests a comforting vacation through a portal to a world of water, he fails to mention that it is also a world inhabited by pirates

Score, Pixel, and Helaine return to Dondar to help their unicorn friends find the former leader of their herd and to fend off a dangerous wizard

Armed with their own magic and a unicorn's horn that can repel the magic of others, Score, Pixel, and Renald finally come face-to-face with the evil Sarman who needs to kill them in order to become supreme ruler of the Diadem universe

Score, Helaine, and Pixel return to Earth in search of a locket to help Score regain his magical powers, but first they must contend with police, gangsters, and New York City traffic