Voyage of the Damned aka Doctor Who Christmas Special. SPOILERS, so enter not lest ye be ken to intergalactic mysteries.
→[More:]Ah, so the Poseidon Adventure, complete with Shelley Winters ...
And we get three lessons of self-sacrifice, though two are obviously foreshadowing the last.
I was surprised that the rumor that Astrid had something to do with the TARDIS (being an anagram) turned out false. I was relieved that they did the "reveal" of it being a spaceship right in the intro, as I worried I'd made a mistake watching the trailer last week (I do hate to be spoiled).
Hm, and I did like the Series 4 trailer, but not as much as the second-half Series 3 trailer with the Master. I just had this feeling that more so than previous specials, this show was a lot of noise and explosions, and the trailer was more noise and explosions. You have to pull it back once in a while, you know, to make the explosions effective.