Summoned by the new, fanatically determined Chief Constable of the Greater Birchester Police, Harriet Martens is started to be greeted with the blunt question, 'Who killed the Preacher?' She is then tasked with making use of the latest DNA techniques to investigate the murder, thirty years ago, of a charismatic youth known as the Boy Preacher, strangled in the empty ballroom of the city's Imperial Hotel. To the scene, she finds, only seven people had access. But forensic laboratory tests fail to do what the Chief Constable expects. And now Harriet has to rely on her ability to make connections which past investigators have missed, and to ferret out the motives of the suspects who have died and the lies they have left behind them...