Joy Taylor has always believed home is the house she lived in her entire life. But then her dad lost his job, and suddenly, home became a tiny apartment with thin walls, shared bedrooms, and a place for tense arguments between Mom and Dad.

Hardest of all, Joy doesn’t have her music to escape through anymore. Without enough funds, her dreams of becoming a great pianist—and one day, a film score composer—have been put on hold.

One bright light comes in the form of her friendly new neighbor, Nora. When she learns about Joy’s need to get away sometimes, Nora lets Joy in on the complex’s best-kept secret: the Hideout, a cozy refuge that only the kids know about. And it’s in this little hideaway that Joy starts exchanging messages on the wall with another kid in the building who also seems to be struggling, until—abruptly, they stop writing back. Joy can’t shake the feeling that someone might be in trouble. She has to find out who this mystery writer is, fast, but between managing a new dog-walking business with Nora, keeping on a brave face for her little sister, and worrying about her parents’ marriage, Joy isn’t sure how to keep her own head above water.