Doctor Who Christmas Special Poster & Details

The Capaldi and David Bradley's First Doctor, as well as introducing Mark Gatiss's Captain, who is central to the timey wimey plot and frozen antics of the episode.

Of course, the hour is more than a meeting of the first and twelfth Doctors; it's the final appearance of Capaldi's iteration of the character and the final episode to be handled by outgoing showrunner Steven Moffat. With that, the episode also promises to introduce Jodie Whittaker's Thirteenth Doctor – which will certainly be a huge draw, as a female take on the character has certainly been a long time coming. But it will also be a chance for Pearl Mackie to return to the role of Bill Potts, the one-and-done companion of the Doctor who brought such a sense of wonder to the show's adventures.

Related: Doctor Who: How To Dress Like The 13th Doctor

As a reminder to everyone that Bill will be back one more time, the BBC has released a new image from the episode, as well as a snazzy animated poster. You can check out the images and read a full synopsis for the episode below:

‘Twice Upon a Time.’ This Christmas. @BBCAMERICA. #DoctorWho pic.twitter.com/WX8ZILzyre— BBC America (@BBCAMERICA) November 28, 2017

Doctor Who Christmas Special Pearl Mackie Peter Capaldi and David Bradley

"The magical final chapter of the Twelfth Doctor’s (Peter Capaldi) journey sees the Time Lord team up with his former self, the first ever Doctor (David Bradley) and a returning Bill Potts (Pearl Mackie), for one last adventure.

Two Doctors stranded in an Arctic snowscape, refusing to face regeneration. Enchanted glass people, stealing their victims from frozen time. And a World War One captain destined to die on the battlefield, but taken from the trenches to play his part in the Doctor's story.

An uplifting new tale about the power of hope in humanity’s darkest hours, Twice Upon A Time marks the end of an era. But as the Doctor must face his past to decide his future, his journey is only just beginning...

Twice Upon A Time is written by Steven Moffat, directed by Rachel Talalay, and executive produced by Brian Minchin. The 60-minute special guest stars Mark Gatiss as The Captain and Nikki Amuka-Bird as the voice of the glass woman, and will see Peter Capaldi’s Doctor regenerate into the Thirteenth Doctor (Jodie Whittaker)."

With the buzz surrounding the episode, the "enchanted glass people" bit may not have been on everyone's radar, but that certainly sounds like a very Doctor Who-like thing to have, especially in a Christmas Special. Gatiss has already featured prominently in the aforementioned clip, so it's safe to say he'll be a fixture throughout the hour, as his war-torn circumstances sound as though they'll be a catalyst for the episode's more "uplifting" aspects.

When, where, and how Bill will come back is anyone's guess, but considering where she was when we last saw her, it stands to reason her return will be when the Doctor needs her the most. It's been an emotional couple of seasons for the Time Lord in of the fates of his companions, so hopefully this episode that's filled with so many goodbyes (and one big hello) will give Capaldi and Mackie's characters a chance for a meaningful farewell.