There was trouble in Xanth again, all kinds of trouble, in fact. The Gap Dragon had escaped from the Gap and was ravaging across the land. The forget spell that had covered the Gap was breaking up into small forget whorls that wandered about giving amnesia to all they touched. Good Magician Humfrey might have had the Answer, but he had overdosed on water from the Fountain of Youth and was only a helpless baby. And Ivy, three-year-old daughter of King Dor and Queen Irene, was lost in the jungles south of the Gap. While Irene sought her without much hope, Ivy was wandering further into danger, her memories ereased by a passing forget whorl. Her path was leading her directly for where the Gap Dragon was seeking dinner.

Summary:

There's trouble in Xanth. A dragon has been terrorizing the vicinity of Castle Zombie, yet Good Magician Humfrey has issued dire warnings against harming it. And an inexplicable, invisible wave of amnesia appears to be sweeping away the memories of countless citizens.

This urgent state of affairs brings King Dor and Queen Irene, along with their 3-year-old daughter, Ivy, to Castle Zombie for an emergency conclave of Magicians.

Humfrey offers his colleagues some surprising and grim news: the rampaging beast is none other than the Gap Dragon- whose survival is essential to Xanth's security. The amnesia, he reveals, is the unfortunate result of miniature forget-whorls that have spun off the Forget Spell.

Dor and Irene, deeply concerned for all of Xanth, are suddenly absorbed in another, more personal dilemma. For a Zombie who has rescued Ivy from a dragon attack has stumbled into a forget-whorl and can't remember where he left her!

Now the frantic Irene must search the wilds of Xanth and find Ivy before she's discovered by one of the land's deadlier inhabitants. It is a search complicated by Ivy's own magical talent, nobody is aware of- especially the young princess herself.