In Rochester, a pre-teen girl is abducted, raped, and murdered. Detective Megan Paige investigates: she works long hours obsessively, and soon she's seeing visions of the dead girl. The FBI profiles the killer as a spontaneous drifter, lucky not to get caught; Megan thinks he's local and a methodical planner. She notes that the victim's first and last names and the place the body was left start with 'C.' When a second murder follows the same pattern, Megan is vindicated, but her obsessions get the best of her, and her mental state impedes her work. With the help of medication, therapy, and a friend, can she regain her equilibrium and catch the alphabet killer?