In this humorous fantasy adventure, Marcus Realwright, traveling elf-magician, learns more than he ever imagined possible about the effects of casting a spell in the presence of a disbeliever in magic. His companion in The Book of Glimmer, a tabby cat called Stub, used to be Eddie, the young Earl of Stubbenfield - but oops, he lied about his (dis)belief in magic, and so Marcus's spell has gone awry and turned the young Earl into a cat. No one is happy about it, except Stub's mom, who is thrilled he's now rid of his many unsuitable girlfriends.

The hope is that by accompanying Marcus on his travels, Stub will be exposed to enough magic that he will become a believer in magic - which is the only way to change him back into a human. But, of course, any spell cast in Stub's vicinity goes awry, so things aren't that simple.

Things get complicated fast when a magical medallion sticks to Stub and won't let go. Together with Andover, their horse companion, Marcus and Stub strive to stay ahead of the evil forces pursuing them. The worst is Tasmin Trident, Evil Lord of Rangamon, who has recently acquired a great deal of illicit power he plans to use to take over the entire tri-country area. But he needs the medallion to do it.

Marcus and friends are shadowed along their escape route by a huge, grouchy orange bird, whom Stub falls for rather hard. After an illuminating encounter with Tasmin and his magical Marcusian globe, Marcus and friends pop into Stubbenfield Manor, where they meet up with Stub's parents - and where the orange bird shows her true feathers as Alex, a sorceress's daughter.

Together they head for the sorceress's cottage, from which the medallion was stolen - and to which it must return. But it's an adventurous, dangerous journey. Their barge trip down the Two-Dots River is wrecked by a vast, fast-moving wall of sludge. When they try to escape the sharp and icy Toorall Mountains, rock-dropping avians cause them serious problems. For some of the travelers, a death-defying slide through the Two-Dots' underwater lava tubes brings the medallion within a few miles of Stonegrown Cottage.

But meanwhile, Marcus has reanimated Tasmin's father, and Larry's not thrilled to wake up after being frozen for 17 years, to find his son Tasmin with his title "Evil Lord." How Marcus and his friends triumph over all these problems, and more, makes for quite a story. It's exciting, but also funny. And there are lessons to be learned - about love, about friendship, about questing for the Good, and about how to defeat a Destroy Vermin spell when all appears to be utterly lost.