A poignant exploration of family and the ties that bind, from New York Times bestselling author Cynthia Hand.

Cassandra McMurtrey has the best parents a girl could ask for; they've given Cass a life she wouldn't trade for the world. She has everything she needs?but she has questions, too. Like, to know who she is. Where she came from. Questions her adoptive parents can't answer, no matter how much they love her.

But eighteen years ago, someone wrote Cass a series of letters. And they may just hold the answers Cass has been searching for.