When Amos Decker returned home 18 months ago to find the bodies of his wife and only daughter, he didn't think he could carry on living. Overwhelmed with grief, he saw his life spiral out of control, losing his job as a detective, his house and his self-respect. But when his former police partner, Mary Lancaster, visits to tell him that someone has confessed to the murders, he knows he has to seek justice for his family. As Decker comes to terms with the news, tragedy strikes at the local school. Thirteen teenagers are gunned down, and the killer is at large. Following the serious brain injury Amos suffered as a professional footballer, he gained a remarkable gift - and the police believe that this unusual skill will assist in the hunt for the killer.