Festive edition of the sci-fi drama. A madcap caretaker greets evacuee Madge Arwell and her two children and leads them into a magical world.
The Doctor (Matt Smith) is the caretaker of recently widowed Madge Arwell (Claire Skinner) and her children Lily (Holly Earl) and Cyril (Maurice Cole) during their holiday vacation away from the London Blitz. The Doctor plans to take them on a treat to a snowy planet through a portal in a present he has placed under the Christmas tree, but Cyril opens it before Christmas and wanders through. While looking for him, the others learn that the trees of the planet are about to be melted down with acid rain for energy.