Imperial Russia, XIX century. Retired lieutenant Alexey Polyansky receives an invitation to serve in the newly formed Gendarme Corps. He was immediately entrusted with the first case: the investigation of the activities of the 'Jacks of Hearts'. This is a gang involved in real estate scams in Moscow and the sale of fake paintings. To the great surprise of the lieutenant, the threads of seemingly banal crimes lead to the disclosure of the ancient mystery of the disappearance of the famous Rose of Versailles diamond, presented by Louis XIV to his mistress Louise de Lavaliere.
Soon, an even more mysterious crime was committed: inexplicable events take place in the Yaroslavl estate of Count Shakhovsky, an avid collector of ancient weapons and armor. The host is visited by the ghost of Count Dracula. Count Shakhovsky dies under mysterious circumstances. The investigation leads Polyansky to a certain Madame Libushe, lady with a very dark past.