Jackie and Milo have been best friends since they were born. Whether they're reading comic books in their tree house hideout, playing video games, or spying on their neighbors using walkie talkies and code names, it's always been the two of them versus the world. But in middle school, things are changing. Milo joins the soccer team and starts hanging out with a new crew. Jackie gets taken under the wing of Adelle, who wants to give her a total makeover and find her a crush. Suddenly, it seems like there are certain acceptable ways to be a girl or a boy, and Jackie starts to feel like everything about her is wrong.

In an effort to get Adelle and her new friends off her back, Jackie sends herself an anonymous love letter. But her plan backfires, and soon Jackie's secret admirer is all anybody at school can talk about. Now she's wondering: Dear Jackie, how are you going to get out of this?