Following their bloody encounter with the Executioner, Sir Maurice Newbury’s assistant Veronica Hobbes is close to death. Desperate to save her life, Newbury and Veronica’s sister Amelia board a sleeper train bound for St. Petersburg, in the hope that Gustav Faberge might have the answer. But there are enemies on board, and Newbury and Amelia will need all their strength and cunning to survive the Revenant Express.