Twenty years ago John Costello's life, as he knew it, ended. He and his beautiful girlfriend, Nadia, were victims of the deranged 'Hammer of God' killer who terrorised New Jersey City throughout the summer of 1984. Nadia was killed instantly. John survived, but withdrew from society, emerging only to work as a crime researcher for a major newspaper. Damaged he may be, but no one in New Jersey knows more about serial killers than John Costello.