When ex-detective Amos Decker returned home eighteen 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, his house and his self-respect. But when his former partner in the police, Mary Lancaster, visits to tell him that someone has confessed to the murder of his family, he knows he owes it to his wife and child to seek justice for them. 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 an extraordinary memory – and the police believe that this unusual skill will assist in the hunt for the killer. When new evidence links the murders, Decker is left with only one option.