Mary Margaret is desperate for a pet. But her father is allergic to almost everything, and her mother is too busy with the new baby coming to focus on finding a hypoallergenic pet for her precocious, nearly-nine-year-old daughter. So Mary Margaret takes matters into her own hands and comes up with some very interesting ideas about how to get a pet, ideas that include harboring a runaway rat, playing farmer for a family of ants, and selling “poop purses” to dog owners in the hopes of raising enough money to get a dog and pay kennel fees.