Doctor Who - The Next Doctor
BBC; BBC America; IMDb; TV.com; Wikipedia

This is the fourth Christmas special of the revived Doctor Who series. It begins with the Doctor arriving in London, on Christmas Eve, 1851. As he wanders about, he suddenly hears a woman shouting for "the Doctor," so he goes to see what's up. There's some kind of creature (called a "Cybershade"), and the Doctor is trying to catch it. But not... no, um... There is a man calling himself "the Doctor," and a Time Lord. And the woman who was shouting before, Rosita (who we kinda like), is serving as his Companion. Anyway, the two Doctors try to capture the Cybershade, and fail. At first, our Doctor thinks this other Doctor must be a future regeneration of himself. The man has lost most of his memory, but he definitely remembers some things that one would expect the Doctor to remember. However, the real reason for this will be made clear later, and I'm not going to spoil it.

Meanwhile, the (current) Doctor tags along with him and Rosita, and he pretends to become the new Doctor's Companion. There are Cybermen on Earth, and they have some kind of plot, which involves the rising of a Cyber-King. Their plot is being aided by a woman named Mercy Hartigan (who we like). She has been promised power and respect in the new order the Cybermen will create, things she has always been denied by men, in spite of her superior mind.

Well... I'm not sure what else I can say without spoiling anything. But of course, the Doctor(s) avert the threat, in the end. And the (new) Doctor's memories eventually return. There is sadness and loss, there are twists to the story, even if few of them surprised me at all. There's a fair bit of humor, and there's some damn cool stuff. All in all, a fairly enjoyable special, if not the best of them.