The acclaimed, New York Times bestselling author of The Book of Ruth and A Map of the World returns with a stunning coming-of-age novel about girls, mothers, and finding one's way in the world.

Seventeen-year-old Phoebe was never interested in her birth family. But on the cusp of her high school graduation, her adoptive mother, Greta, insists on a visit to meet her biological parents and siblings. The encounter is a jolt, a revelation that derails Phoebe.

With the help of her best friend Luna, Phoebe runs away--as far as their friend Patrick O'Conner's chaotic home, where she hopes to go unnoticed among his thirteen siblings. But when Phoebe asks Patrick to chop off her hip-length hair, she's suddenly transformed. Patrick's older brothers can't help but notice the striking, Peter Pan-like stranger who has suddenly appeared in their midst.

What starts as an adolescent rebellion soon spirals into a whirlwind of self-discovery and unexpected connections. As she grapples with her shifting identity and strained relationships, Phoebe must navigate the tumultuous road out of girlhood and chart a new and unknown course.