In the winter of 2004, a shy woman named Emma sits in Toby's office. She wants to share this wonderful new book she's reading, but Toby, her therapist, is concerned with other things. Emma is transgender, and has sought out Toby for approval for hormone replacement therapy. Emma has shown up at the therapy sessions as an outgoing, confident young woman named Katina, and a depressed, submissive workaholic named Ed. She has little or no memory of her actions when presenting as these other two people. And then Toby asks about her childhood. As the story unfolds, we discover clues to Emma's troubled past, and how and why these other two people may have come into existence. As Toby juggles treating three separate people, each with their own unique personalities and memories, he begins to wonder if Emma is merely acting out to get attention, or if she actually has Dissociative Identity Disorder. Is she just a troubled woman in need of help? And is "the third person" in her brain protecting her or derailing her chances of ever finding peace?