New Doctor Who Christmas Special Trailer Teases Capaldi's Regeneration

Is there a Doctor in the house? Come Christmas on the BBC, the answer is going to be a big, fat, yes -- and then another one, just for good measure. A new trailer for the Doctor Who Christmas Special reveals the TARDIS parked in a snowy landscape, where the Twelfth Doctor (Peter Capaldi) is about to encounter... himself, in the form of the very first Doctor (David Bradley).

From the looks of it, the two Doctors will have to team up for an action-packed, world-saving romp through time and space, which will also be Capaldi's last. After "Twice Upon a Time" airs Christmas night, the actor will exit Doctor Who and be replaced by Jodie Whittaker, the franchise's first female Doctor. In the final few moments of the trailer, fans can catch a glimpse of Twelve's regeneration on board the TARDIS -- a process that began in the Season 10 finale.

The BBC will lead in to the Christmas special with a week-long, 24-hour marathon of Doctor Who episodes. For a sneak peek at the twin alien action to come, check out the full trailer above.

The Doctor Who Christmas special will air December 25 at 9/8c on BBC America.