The Doctor Who Christmas Special, Twice Upon a Time, will see Peter Capaldi's last time portraying the Time Lord as well as the exits of long-time writer Mark Gatiss and showrunner Steven Moffat. This year's Christmas Special heralds Moffat's last hurrah, while Mark Gatiss plays a World War I soldier out of time known only as "The Captain." It's also supposedly a really moving episode, according to Gatiss who promises some surprises for the end of this era of the hit show. In addition, the Christmas Special will be the introduction of Jodie Whittaker's new incarnation of the titular Time Lord. The episode is directed by Rachel Talalay, who oversaw 2015's popular Heaven Sent episode, and is written by showrunner Steven Moffat.

As previously revealed in the closing moments of the season finale, the special will feature Peter Capaldi's current Doctor team up with the First Doctor, played by David Bradley. The biggest clue to the plot of this year's Christmas special came in the closing moments of the episode when Capaldi's character struggled out of the Tardis into a snowy wasteland and came face to face with the original Doctor. The Christmas Specials are always fan-favorites and this one might go down as one of the best.

While talking to Entertainment Weekly, Mark Gatiss spoke about how emotional this year's special will be when compared to past years. Fans are going to be see the passing of the torch as well as a regeneration from the First Doctor, which already makes it special. In addition, it's also Gatiss' last episode. Gatiss had this to say about the Christmas Special.

"It's essentially a kind of chamber piece of David, and Peter, and Pearl, and me, and this strange mysterious threat. But really it's about the wonderful interplay between the two Doctors. Both Doctors are about to regenerate, one of them for the first time, one for the 13th, or whatever it is now. (Laughs) It's a very charming, funny, and rather moving script, and it was just a privilege to be part of it. I mean, for me, as a lifelong fan, to be in a regeneration story, and to be in Peter's one, and to be also with the First Doctor, it was amazing. I just had to pinch myself at times. I looked across the set to see two TARDISes next to each other and got a real frisson of old-school Doctor Who-ness."

Jodie Whittaker has been announced as the next Doctor and she will be the first female to play the lead in the long-running Doctor Who series. When it was revealed that Whittaker was taking over, backlash began to spread amongst certain factions of Doctor Who fans, many saying that they will boycott this season just because of that reason. Doctor Who fandom may only rival Star Wars in terms of feeling personally hurt by decisions made by the franchise. Regardless, the Christmas Special will be her first episode and Peter Capaldi's last episode unless he shows up sometime down the line.

Related: Doctor Who Season 11 Premiere Date Announced, Big Change Revealed

As previously noted, the Doctor Who Christmas Special is entitled Twice Upon a Time and it will premiere on December 25th. This will be the 13th Christmas Special for Doctor Who and as writer and co-star Mark Gatiss has said, it's going to be an emotional one, so maybe break out a box of tissues while you watch. You can read more about what Mark Gatiss had to say about the Doctor Who Christmas Special courtesy of Entertainment Weekly.