Ep 1. Twice Upon a Time

In the Doctor Who Christmas Specials season 6 episode 1, titled "Twice Upon a Time," the Doctor finds himself teaming up with a familiar face- his first incarnation from 1963. The two Doctors are thrown together in a mysterious, snowy landscape, caught in a time glitch. As they try to work out why this has happened to them, they stumble upon a World War I Captain, stranded in the same time period. Together, they embark on an adventure to find their way out of the glitch and figure out what fate has in store for them.

The episode is packed with emotional moments as the two Doctors come to terms with their differences and similarities, with the first Doctor initially struggling to understand the much-changed world he finds himself in. There are nods to past companions and enemies of the Doctor, as well as some fun moments as the two Doctors race against time to find a way out of their predicament. The World War I setting gives the episode an added layer of depth and meaning, highlighting the horrors of war and the importance of peace.

Overall, "Twice Upon a Time" is a heartwarming and exciting episode, filled with adventure, twists, and surprises. It's the perfect way to send off the beloved 12th Doctor and welcome in a new era of the show.