'Doctor Who' plot news, spoilers: Preview of Christmas special to be released at SDCC; former companion to appear?

Peter Capaldi as the titular character in "Doctor Who"Twitter/bbcdoctorwho

Series 10 of "Doctor Who" is now officially over and that comes with departures of several characters, most of them for the time being. As fans everywhere are now gearing up for the Christmas special, a sneak peek of the episode will be revealed at the Comic-Con International: San Diego.

Along with the news of series 10 being showrunner Steven Moffat's last is also the news of star Peter Capaldi leaving the show as well. This means a new Doctor will be coming in 2018 and from what happened in the series 10 finale, a new companion as well. The show will be having its last panel at the convention with Capaldi, along with his co-stars Michelle Gomez, Matt Lucas and Pearl Mackie. Moffat and actor Mark Gatiss, who has also written episodes for the show, will also be joining the panel, which will be moderated by Nerdist's Chris Hardwick.

Fans who are going to attend the SDCC will not only get to hear about the cast's memorable moments before, during, and after filming, they will also get to see a little preview of the Christmas special. Any Whovian can agree that when it is the last special for the current actor playing the Doctor, these festive episodes will seem bittersweet. However, this year's Christmas special is going to be a lot more exciting for a few reasons.

The show goes full circle when the Twelfth Doctor meets his original face. "Game of Thrones" actor David Bradley has returned to the series as the First Doctor. As shown in the last scene in the series 10 finale, the two Doctors met in a snowy place, just when the Twelfth Doctor was trying to hold back on regenerating.

There is another reason many are looking forward to the Christmas special? According to The Mirror, a former companion is making her return in the episode. Jenna Coleman, who plays Clara Oswald on the show, will be making an appearance. It will most likely be to see Capaldi off before the new Doctor takes over, as it has become a tradition for former companions to appear in their respective Doctor's last episode. Mackie's appearance on the special has yet to be determined.