Guest Stars Barbara Hershey as Caroline Hubbard Brian J. Smith as Hector MacQueen Hugh Bonneville as Edward Masterman Toby Jones as Samuel Ratchett David Morrissey as John Arbuthnot Jessica Chastain as Mary Debenham Samuel West as Dr. Constantine Eileen Atkins as Princess Dragomiroff Marie-Josée Croze as Greta Ohlsson Denis Ménochet as Pierre Michel Sam Crane as Lt. Blanchflower Serge Hazanavicius as Xavier Bouc Tristan Shepherd as Lt. Morris Susanne Lothar as Hildegarde Schmidt