Dragon on a Pedestal (Magic of Xanth #7)

There is 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, as lost in the jungles...