Autumn of 1829, Smolensk Governorate. A local landowner—Prince Seversky—has a wedding! A hospitable home, a festive table, a colorful fireworks display—nothing seemed to foretell trouble. But fate has other plans… In the morning after the grand celebration, the prince is found dead in his bed—yet in his arms is not the bride, but his lover, Nastya! The main version of the death is poisoning by carbon monoxide. “Amateur sleuths” gather from the whole estate: they get in the way underfoot, obstruct every step. And above all—St. Petersburg doctor Ilya Andreevich Tonner, who has an entirely different version of what happened…