Peter Capaldi’s final episode of Doctor Who this Christmas will feature Pearl Mackie as Bill Potts and be called Twice Upon a Time, it was revealed this evening (23 July) during a cast panel at San Diego Comic Con. Viewers will have to wait until Christmas to discover exactly how Bill, who will appear throughout the episode, makes her return.

The series introduces Pearl Mackie as Bill Potts, and also features Matt Lucas as Nardole. Michelle Gomez and John Simm return as their respective incarnations of the Master. The main story arc for the first half of the series revolves around the Doctor and Nardole occupying themselves at a university while they guard an underground vault containing Missy. Missy later travels with the team in the TARDIS, and eventually partners with her previous incarnation as they battle a Cyberman onslaught.

Join the Doctor, as he teams up with an investigative journalist, and a superhero to save New York from a deadly alien threat.

The Doctor and Clara face their Last Christmas. Trapped on an Arctic base, under attack from terrifying creatures, who are you going to call? Santa Claus!

special episode of Doctor Who

It’s the deepest part of winter, the exact midpoint, Christmas Eve – half way out of the dark. Amy and Rory are trapped on a stricken space liner that’s plummeting through banks of thick icy fog to the surface of the planet below. Only one man has the power to save them; only one man is in possession of a machine that can clear the fog and let them land safely. That man is Kazran Sardick, a rich but lonely old miser who rules Sardicktown with a sky-mast of iron. The Doctor’s only chance of rescuing the ship’s 4,000 passengers is to save Kazran’s soul and show him that life is worth living. For this he needs to go back, way back, to when Kazran was a boy with a life full of promise. But can the Doctor put a song in Kazran’s heart and love in his life, in time for Christmas? Can he bring him out of the dark?

special episode of Doctor Who

special episode of Doctor Who

2013 special episode of Doctor Who

The main story arc of the series focused on the significance of the character of Clara, whom the Doctor had encountered twice before as Oswin in "Asylum of the Daleks" and as a governess in "The Snowmen". It also features the recurring appearance of the Doctor's enemy, The Great Intelligence.

special episode of Doctor Who

The Doctor returns, alongside newly weds Amy and Rory, to face monsters and mysteries and adventures all across time and space. Together they find themselves in sixties America, battling the invasion the world forgot, then aboard a pirate ship on the high seas of 1696, to solve the mystery of the Siren. In a bubble universe at the edge of reality, the Doctor meets an old friend with a new face.

Episode 1: The Eleventh Hour Episode 2: The Beast Below Episode 3: Victory of the Daleks Episode 4: The Time of Angels Episode 5: Flesh and Stone Episode 6: The Vampires of Venice Episode 7: Amy's Choice Episode 8: The Hungry Earth Episode 9: Cold Blood Episode 10: Vincent and the Doctor Episode 11: The Lodger Episode 12: The Pandorica Opens Episode 13: The Big Bang