Alexander always seems to create a ruckus. The family he lives with screams when they see him and chase him with a broom. One day, he meets another mouse, Willie, who looks just like him, small and gray. Except this mouse has two wheels, instead of legs, and a key in his back. The fact that this mouse is the little girl Annie's favorite toy makes Alexander very sad: "They don't care much for me," he tells Willie. One day, Willie tells Alexander of a magic lizard who has the power to change one animal into another. But will this lizard actually help Willie when he needs it the most?