This is a faithful adaptation of the book by Boris Akunin.
The Russian Empire, the end of the 19th century.
On a train from St. Petersburg to Moscow general Khrapov was killed and no one else but Erast Petrovich is under suspicion because the killer pretended to be Fandorin. There are initials BG on the handle of the knife Khrapov was stabbed with, the initials belong to a terrorist organization which keeps both capital cities (Moscow and St. Petersburg) in fear. This time Fandorin is not the only one trying to solve the crime, general Pozharski, a famous detective takes over the investigation.