A foundling adopted by wealthy parents, Riley led a privileged life until she fell in love with Fiona Bell, an evangelical preacher's daughter. Raging hormones, the full moon, and the pull of Fiona Bell on her teenage heartstrings triggered her first transformation. Unfortunately, her parents witnessed the change and sent her off to college with a trust fund and an agreement never to return home.

Twenty years later, Riley shares a lucrative therapy practice with Dr. Margaret Spencer. Margaret, her wife, and her gay brother-in-law are the only ones who know Riley's secret. Afraid of risking exposure, Riley restricts her love life to online hookups. But when a family is referred for treatment and Fiona Bell comes back into her life, all the rules of the client-therapist relationship are tested and Riley's world is turned upside down.