Fifteen-year-old Maggie's problems seem ordinary: She has tiffs with her too-critical mother, a crush on her cute psychologist, and worries that her only friend is morphing into a popular girl, leaving her behind. But Maggie has a few not-so-ordinary problems. A voice in her head is telling her to kill-and not just anyone. Each time the target is a person who has done something terrible to someone Maggie cares for. As the voice's demands escalate, her world begins to crumble.