To begin, this book is geared towards young adults. It is meant to be a fun read, without the burden of a heavy plotline. If you are looking for something with a ton of substance, you will not find that in the Xanth series.
I originally read this book when I was a freshman in high school on a long drive to South Dakota to visit family in the summer. We stopped at a used book store and the cover (I know, I know, never judge a book by its cover) was so intriguing to me that I picked up the book without having ever entered the beloved world of Xanth previously. I loved the story so much, that I read it at least three times again afterwards in that same summer. Now it is over 15 years later and I went through a re-read of this book that I loved so much. As Goodreads didn't exist then, I felt it was time for a proper review of the book... here it goes....
You are first introduced to Tandy, a teenage half nymph/half human girl that lives underground with her nymph mother. Her father is a soldier that spends the majority of his time working for the King above-ground at Castle Roogna. Unfortunately, in her exploring of the underground caves, she was discovered by a demon who has now taken a fancy to her. Inexperienced with men of any sort besides her father, she was understandably terrified. Her mother, being the type of nymph that she was, was unable to offer her any sort of assistance when away at work, and refused to believe that any demon would act out so maliciously. So Tandy had to figure out a way to get herself out of the situation.
She plans on finding her father, and rides a nightmare to the surface. Having no experience with the surface, she tells the nightmare that she will release her if she drops her off at Castle Roogna. By the time the sun starts to appear, she is dropped off at a castle...but the wrong one!
Next you meet Smash, a half human/half ogre male that reacts as though he is fully ogre... for the most part. Having grown up around humans, he tends to stay away from the eating of humans lest he ruin his friendships. For some reason, he is not satisfied with his life and makes a trip to Good Magician Humphrey for an answer. When he gets there, he cannot even find enough intelligence to ask his question! However, Good Magician Humphrey decides that his answer is to escort Tandy (who has been serving her year for her question she asked when dropped off at the castle) throughout Xanth. Both Smash and Tandy are confused by this turn of events, but roll with the punches anyways.
Tandy has no experience above-ground and it is up to Smash to teach her what is good and what is to be avoided in Xanth. However, Tandy has a heart of gold that wants to help all creatures, and soon Smash ends up escorting 7 different females of different species across Xanth to find what they are looking for as well. There is no end to the excitement, Smash becomes super intelligent when he stumbles into an Eye Queue vine, has to fight for his soul in a hypnogourd, fights dragons, tangle trees and other ogres just to save his newly found female friends.
Without spoiling anything else in the book, it is a great read about not judging a person by their looks, but instead by their hearts. I recommend it for all ages, and there is no need to read the other Xanth books to fully get immersed in this one!