'Doctor Who': First Clip From The 2017 Christmas Special Released

The First Doctor gets a glimpse of his far future in the first clip released from this year's Doctor Who Christmas Special, "Twice Upon A Time."

In the clip, The Twelfth Doctor (Peter Capaldi) escorts the First Doctor (David Bradley) and the Captain (Mark Gatiss) into the TARDIS. The First Doctor is shocked by what he sees, a TARDIS that does not at all resemble his own, while the Captain is taken aback by how the TARDIS is bigger on the inside.

The Twelfth Doctor then drops some spoilers about World War I and the First Doctor, upon realizing who the Twelfth Doctor is, laments that he won't be getting any younger.

Take a look at the video above.

This year's Doctor Who Christmas Special will be the final episode for Peter Capaldi as the Twelfth Doctor. It will also be the final episode created under the guidance of outgoing showrunner Steven Moffat, who has guided the franchise since 2010, and the last to feature Pearl Mackie as companion Bill Potts.

The episode is also expected to feature the first official appearance of Jodie Whitaker as the Thirteenth Doctor, who will become Doctor Who's first female lead in season eleven.

Chris Chibnall, the creator of Broadchurch and a former writer on Doctor Who spinoff series Torchwood, will take over as the new showrunner on Doctor Who. The series will reportedly undergo some big changes under Chibnall next season.

Earlier in November, the BBC revealed the first look at Whitaker in full costume as the Thirteenth Doctor.

The Doctor Who Christmas Special may have some more surprises in store for fans as both Matt Smith, the Eleventh Doctor, and a former Doctor Who companion are rumored to appear in the episode.

"Twis Upon A time" brings the Doctor face-to-face with his past as the TARDIS brings him back in time and lands him in the middle of the classic Doctor Who episode "The Tenth Planet," where the Twelfth Doctor, fending off regeneration himself, finds the First Doctor in much the same situation.

The Doctor Who Christmas Special will air on Christmas Day on BBC America. The episode will also be shown in select movie theaters on December 27, 2017, thanks to Fathom Events. The theatrical screening will be accompanied by two bonus features celebrating Peter Capaldi's time as the Doctor and Steven Moffat's tenure as the series' showrunner. Locations and more information are available at the Fathom Events website.