The year is 1871. Prince von Ahrensburg, Austria's military attaché to St. Petersburg, has been killed in his own bed. The murder threatens diplomatic consequences for Russia so dire that they could alter the course of history. Leading the investigation into the high-ranking diplomat's death is Chief Inspector Ivan Putilin, but the Tsar has also called in the notorious Third Department - the much-feared secret police - on the suspicion that the murder is politically motivated. As the clues accumulate, the list of suspects grows longer; there are even rumors of a werewolf at large in the capital. Suspicion falls on the diplomat's lover and her cuckolded husband, as well as Russian, Polish and Italian revolutionaries, not to mention Turkish spies. True to his maxim that "coincidence and passion are the real conspirators," Putilin seeks answers inside the diplomatic circus as well, which leads him to struggles with criminals and with the secret police itself. When the mystery is solved, the only person who saw it coming was Putilin.