The Doctor is on the Titanic. No, not the ship Titanic that sank a hundred years ago. A spaceship named after that ship, which is sort of a cruise vessel. I didn't really like this episode. It was really predictable (though I didn't, and, indeed, couldn't have noticed that the owner of the stand was Donna's grandfather--spoiler!) and boring. Yeah, I didn't love it. The only Christmas special I've really enjoyed was the one where David Tennant was introduced...anyways...onwards!