Retired captain Artemy Aristov is a born detective. The death of a passenger on a train going to Nizhny Novgorod seems quite natural - a heart attack. But Aristov proves that this is a sophisticated murder committed in order to take possession of secret government documents. The detective and his young assistant Baron Daguerre are on the trail of a mysterious stranger in pince-nez with blue lenses. This is a virtuoso killer with unique abilities. While hunting for a criminal, detectives discover a powerful secret organization that is going to radically change the course of history...