Autumn 1829, Smolensk Governorate. The local landowner, Prince Seversky, is getting married! A welcoming house, a festive table, a colorful fireworks display—nothing seems to foretell disaster. But fate has other plans… In the morning after the lavish celebration, the prince is found dead in his bed, yet in his arms is not the bride, but his lover Nastya! The main theory is death by carbon monoxide poisoning. Whole house full of volunteer “detectives”: they get underfoot, мешают each step. And above all is the doctor from St. Petersburg, Ilya Andreevich Tonner, who has an entirely different version of what happened…