Rue Silver's life is not what it appears to be. Her mother is a faerie, and has been taken back to the faerie realm. As Rue goes to bring her back, she must travel deep into an inhuman world. At the same time, the faerie realm is venturing into our world too, and taking its toll on those Rue loves. When her grandfather's plans threaten Rue's city, she realizes that she's the only one who can stop him. But is Rue a human or a faerie?