Twas the night before Christmas, and all through the house not a creature is stirring...
Except the Doctor, and Hannah. Oh, and the evil alien Santa stalking them through the corridors. As the bodies pile up in a house riddled with secrets, the Doctor must find the killer before it's his turn. Meanwhile, Hannah harbors a secret of her own that could destroy her relationship with her best friend.
Careful with that mistletoe. Stay well away from the plum pudding. And whatever you do, pray you don't find a lump of coal in your stocking. Because this is one Christmas when you really, really had better watch out!