January 2006. In the Swedish hamlet of Hesjövallen, nineteen people have been massacred. The only clue is a red ribbon found at the scene. Judge Birgitta Roslin has particular reason to be shocked: her grandparents, the Andréns, are among the victims. The police insist that only a lunatic could have committed the murders. But when Birgitta discovers the diary of another Andrén - a gang master on the American transcontinental railway in the nineteenth...