Cerber – The action takes place in winter 1826 in St. Petersburg. After the rebellion on Senate Square was successfully suppressed, an investigative commission began searching for the protesters. Some of them were found thanks to informants. Suddenly, a series of brutal murders occur in the city: the victims are those who wrote informants on the Decembrists. The criminal leaves a paper with a poem by Alexander Pushkin near the bodies. The investigation is taken up by the capital detective and nobleman Alexander Boshnyak.