Sisters Dara and Nick used to be inseparable, but that was before Dara kissed Parker. That was before the accident that left Dara's face scarred. Now the sisters totally estranged. When Dara vanishes on her birthday, Nick thinks Dara is just playing around. But another girl, Madeline Snow, has vanished, too. Nick becomes increasingly convinced that the two disappearances are linked-- and she has to find her sister, before it's too late.

Told through journal entries, a psychotherapist's notes, court records, and more, relates the tale of Carly, a teen who was institutionalized after her parents' death but released to Elmbrige High School, where she is believed to have a second personality or soul named Kaitlyn, and/or be possessed by a demon.