Zoe knows she doesn't belong in a hospital. So why is she in one? Twin Birch isn't just any hospital. It's a strange mansion populated by unnerving staff and glassy-eyed patients. It's a place for girls with serious problems; spindly girls who have a penchant for harming themselves. Zoe isn't like them. Through letters to her best friend, Elise, Zoe tries to come to terms with why she was sent to Twin Birch against her will. But Elise never writes back. Alone and trying to navigate tenuous friendships and bizarre rules, Zoe finds that the reason for Elise's silence lies in memories of their beautiful, inescapable, and sometimes suffocating friendship. A friendship that has both saved her and may still destroy her--unless she is able to confront the truth about her past once and for all. "A psychological zinger . . . will keep readers invested to the last page."--Kirkus, starred review