Jessica is a gangly teenage girl being raised by her gorgeous, but over-worked, single mother. Jessica has few friends her age, and spends much of her free time reading and imagining things. One day, she discovers an abandoned newborn kitten, which she names Worm due to his lack of sight and extremely short fur. As Worm gains strength, Jessica starts to believe that Worm is talking to her, and forcing her to do bad things. Feeling less and less in control of her actions, Jessica seeks a way to free herself of these compulsions.
This book exhibits the following tropes:
- Ambiguous Ending: Whether or not Worm was possessed or it was a product of Jessica's imagination and state of mind is left up for interpretation.
- Cats Are Mean: Worm is not a very happy cat, and possibly evil. However, his mean behavior and evil attributes could be because Jessica is not at all very nice to him.
- Cute Kitten: Subverted by Worm. He is a bald, ugly kitten — hence his name.
- Disappeared Dad: Jessica's dad ran out on them shortly after Jessica was born.
- Evil-Detecting Dog: Mrs. Fortune's cats are afraid of Worm, and avoid Jessica after Worm arrives. Then again, Mrs. Fortune points out that they're old cats who have trouble dealing with new things like kittens.
- Familiar: Worm is implied to be a Witch's familiar. He may or may not be Jessica's.
- Kids Are Cruel: Jessica has shades of this.
- Maybe Magic, Maybe Mundane: It's unclear as to whether Worm was indeed a witch's familiar, or if Jessica is essentially talking herself into her belief in witches.
- Obfuscating Insanity: Jessica attempts this to get out of trouble a few times, feigning an Ambiguous Disorder. She quickly learns that doing this gets people talking about institutions and special tutors rather than excusing one's actions.