1878. Larissa Kirsanova, a young mathematics teacher, arrives in a small provincial town of Bogorodsk. Miss Kirsanov is brought here by the desire to find her fiancé, a young nobleman Pavel Bestuzhev, who mysteriously disappeared the day before their wedding, without saying goodbye or even leaving a letter. Pavel comes from Bogorodsk, where there only his old mother remained of his relatives. Larissa's favorite aunt, Lizaveta Prokofyevna, also lives here. Meanwhile, veterans of the Russian-Turkish war return war from the Balkans after the war's end. The whole town rejoices when meeting the heroes. On her arrival in the province, Larisa has no clue of a completely different type of life awaiting for her here, where her amazing abilities, intelligence and character will be fully revealed. From now on, her life will be full of mysteries, risk and disclosure of high-profile crimes.