The BBC Press Office have released the official synopsis for the Christmas episode, "The Doctor, The Widow and the Wardrobe":
It’s Christmas Eve, 1938, when Madge Arwell comes to the aid of an injured Spaceman Angel as she cycles home, in this year's Doctor Who Christmas Special, starring Matt Smith as the Doctor.
He promises to repay her kindness – all she has to do is make a wish.
Three years later, a devastated Madge escapes war-torn London with her two children for a dilapidated house in Dorset. She is crippled with grief at the news her husband has been lost over the channel, but determined to give Lily and Cyril the best Christmas ever.
The Arwells are surprised to be greeted by a madcap caretaker whose mysterious Christmas gift leads them into a magical wintry world. Here, Madge will learn how to be braver than she ever thought possible. And that wishes can come true...
Madge Arwell is played by Claire Skinner, Lily Arwell by Holly Earl and Cyril Arwell by Maurice Cole.