1826 After the suppression of the uprising on Senate Square and the arrests, a series of brutal murders of those who informed on the Decembrists took place in St. Petersburg. Near his victims, the killer leaves a note with a line from a poem by the young poet Alexander Pushkin. Moscow detective Lavr Petrovich Perekhodov and nobleman Alexander Boshnyak take up the case. But this case is a reason to investigate other crimes. The story that formed the basis of the series “Cerberus.”