|aIt is about 5 kids: Rachel, Casey, Marco, Jake, and Tobias. They call themselves the animorphs. The can morph (change) into anything theywant when they concentrate. In the book an evil alien Yeerk slug takes over the body of the kid's vice-principal, Mr. chapman. Mr. Chapman has a cat named Fluffer and Rachel morphs into a cat that looks just like Fluffer to spy on him. Chapman figures out that it isn't his real cat! Then a big fight starts between the evil aliens and the animorphs.