1885 The postmaster in Kolomna, Felix Yanovich Kolbovsky, witnesses how the merchant Grivov receives a letter that causes him indescribable joy. However, the very next day the merchant is found hanged. This seems strange to Kolbovsky, and the merchant’s wife is sure that he could not commit suicide. Felix Yanovich convinces his friend, forensic investigator Kutilin, to continue the investigation. And Kolbovsky himself, fascinated by the emerging science of graphology, is simultaneously looking for the killer, analyzing the handwriting of all the suspects.