Regan has always been there for her transgender brother, Liam, sacrificing her needs for his, but when he announces that he is ready to 'transition' into Luna permanently, Regan is not sure she can handle the consequences.

Told from Regan's point of view in the present and in flashback, this novel breaks new ground in Young Adult literature with a sensitive and poignant portrayal of a young man's determination to live his true identity and his family's struggle to accept Luna for who he really is.