Detective Kate Snow and Detective Ally Emerson are barely home from their Scottish adventures when the past comes crashing back into their lives. A child is dead. An eight-year-old. And the details are chillingly familiar. The murder mirrors the very first case that brought Emerson and Snow together-a case they believed was closed for good. The killer, Michael Ratcliffe, is already behind bars. He can't be responsible. Or can he? As doubt creeps in, everything they thought they knew begins to unravel. Did they put the wrong man away? Is a copycat stalking their town? Or has something far more disturbing been overlooked? Pulled back into the investigation that ignited their partnership, Snow and Emerson race to uncover the truth before another life is lost. As the pressure mounts, so does their connection. With danger closing in and emotions running high, long-unspoken words finally surface-changing everything between them. Can they stop a killer in time? And with their relationship reaching a new depth, what kind of future awaits them? Find out in… By the Book.