London, 1811. The city was shocked by monstrous crimes - seven people died at the hands of a killer: all the relatives of Marr, a shopkeeper, and the family of Williamson, a pub owner. The brutal killer did not even spare children. However, the investigation was carried out hastily, and the main suspect hanged himself in prison. He was immediately declared guilty - just to reassure the residents... But the mystery of the brutal murders continued to haunt the minds of lovers of the dark secrets of the past for two centuries. Who actually committed these atrocities? F.D. James and the famous British historian T.A. The Critchleys conducted their own investigation. Who do they think is the real killer?..