So this is another one from season four. Theres going to be yet another later. Sorry, but it really was a great season of stories! This story is a quiet little affair where the Doctor, his companion, Lucie Miller (Sheridan Smith), are joined by his granddaughter, Susan (Carole Ann Ford), and her son, the Doctors great-grandson, Alex (Jake McGann), for Christmas in the TARDIS. Its going to be a delightful time, with no possibility at all that things could all go horribly wrong I do very much enjoy this story. Its a nice, contained little tale that ties into the larger arcs but isnt reliant on them. As long as you can grasp the idea that Alex is Susans son (hes introduced in a story that shows up on this list later), then youll be fine, and youll be in for a really sweet, delightful story.