St. Petersburg, 1829. The city is shaken by a series of suicides and unfortunate accidents: Count Ukhtomsky is shot, Lieutenant Repetin breaks his neck after falling from a horse, and Baron Baumgarten is found hanging. The police attribute everything to a random concurrence of circumstances, but the coroner, Ilya Andreevich Tonner, thinks otherwise. He manages to uncover a highly interesting detail: in this case a woman is involved, her face hidden beneath a veil. Tonner is certain that the woman knows many secrets, including the mysteries behind the murders that occurred…