We all know Michelle Dockery will be gracing our screens on Christmas Day as part of the much-anticipated Downton Christmas special, but fans of Lady Mary will be pleased to hear the 30-year old star is also appearing in the BBC1 adaptation of William Boyd's Restless just two days later.

Joining a star studded cast that includes Michael Gambon, Charlottel Rampling, Rufus Sewell and Hayley Atwell, Michelle plays Ruth Gilmartin. One day in 1976, Ruth's mother reveals that she has been living a double life as is actually a spy who has been on the run for the last 30 years. 

Producer Hilary Bevan Jones has said of the two part drama: "Restless weaves a great love story within a riveting espionage thriller. Trust, betrayal and the need to escape the past are at the heart of this story."

Restless starts on 27 December on BBC1 at 9pm