Katie thinks Melody is a boy magnet, while she thinks of herself as more of a boy repellent. Melody's parents never make her do any chores, while Katie gets stuck babysitting almost every day. And Melody's parents are still married. Katie's are too...just to other people. Meanwhile, Melody thinks Katie's house is fun and lively, while her own house is empty and lonely. Her dad almost never comes home, while Katie has family dinners practically every single night. And everyone always talks about how pretty Melody is, like that's the most important thing, like that's all she is... There's no doubt about it: Katie is insanely jealous of her best friend, Melody. As it turns out, Melody is jealous of Katie too. And when they both wish for the exact same thing at the exact same time — for the chance to redo summer in each other's place — their wishes come true. Katie is Melody and Melody is Katie, and neither one has the experience she expected.