An orange cat named Mortimer sits in front of a mouse door in a basement. He has numbered the five doors and waits for three mice to enter door number four. He is frustrated by the misconception that cats are heartless and unfeeling. When the mice appear, Mortimer ushers them in and then back out through another door, knowing that the homeowner, a woman named Al, does not approve of mice in the house. The mice comment on Mortimer having six toes on each paw.

Al comes to the basement, picks up Mortimer, and stares at a library cart. Mortimer recalls when he and his sister, Petunia, used to play in the library as kittens. Suddenly, Al goes upstairs to wake Ms. Scoggin and give her some apple muffins she has just baked. She tells Ms. Scoggin she has a plan.

Mortimer follows Al, who lugs a book cart outside. He worries about these remnants of his library, knowing he was meant to look after it. Al has taken the doors and hinges from the house’s cheese cupboard and is fashioning a new cupboard from them.