This book is about a possessive cat that is harmful to humans. When Sally finds an abandoned cat, she keeps it as a pet. Suddenly, moments later, the cat scratches her and then she turns into a cat. Whenever the cat scratches a person, that person trades place with the one that has been turned into a cat and they will turn normal again, but the other person will turn into one and so forth. This cat is possessive. This is a mystery you would never forget.