Up in a Heaval

It might have been the merest chance that brought Umlaut to Castle Zombie that morning and launched him on a harrowing adventure. But in the magical land of Xanth, things are seldom left to chance, and adventures lurk around every corner.
An unassuming young man with an uncanny knack for attracting lovely young ladies and an uncommon talent for emulating anyone he wished, Umlaut was forced to flee a flock of overly friendly females by disguising himself as a Zombie girl. In his haste to find a hiding place, he found himself face-to-face with a dreadful dragon and feared he would soon meet his end. But in Xanth, things are seldom exactly as they seem, and he soon discovered that the dragon was really a sinuous female sea serpent named Sesame, with a gift similar to his own, who had become accidentally entrapped in the Castle's dungeon.
When the two happen upon a packet of mail from Earth delivered by mischance to the Zombie King, they inadvertently set in motion a sinister scheme that could spell the end of Xanth. A letter they forward to the Demon Jupiter unexpectedly enrages him, causing him to send his own Red Spot hurtling toward Xanth. Soon everything is up in a heaval, for no one knows how to avert this interplanetary peril. Even the Good Magician Humfrey is baffled, for some strange force has obscured the future. In desperation, he instructs Umlaut and Sesame to deliver the remaining letters to their far-flung recipients, in the faint hope that this may somehow stop the Spot.