The film is based on the second book from the Adventures of Erast Petrovich Fandorin series of novels written by the Russian author Boris Akunin. The film takes place in 1877 during the Russian-Turkish war. Erast Fandorin has just escaped from Turkish prison and is trying to get on the Russian side as soon as possible to give important information about the upcoming attack of the enemy. On his way he meets Varvara Suvorova, a young lady who is going to see her fiancée - a soldier of the Russian army. Erast also knows that there is a spy somewhere in the Russian army, everyone is under suspicion…