Parts: 1 (60-minute)
Writer: Steven Moffat
Airdate: 25 December 2013
Production Code: n/a

Doctor: eleventh
Companions: Clara

Creature Feature: Daleks, Cybermen, Silence, Weeping Angels, Sontarans
Special Guests: the Time Lords

Story: From an isolated ringed planet, a mysterious signal begins broadcasting across the universe, drawing to it a wide variety of alien races in whom it evokes an instinctive response of fear. The Doctor, investigating the signal, discovers that among the alien races gathered around the planet are the Daleks, Cybermen, and the Papal Mainframe, who have established a barrier to prevent the various factions from landing. The Doctor is able to get special dispensation from the Mother Superius for himself and Clara to visit the planet, on the condition that they investigate the transmission and report back to her.

On the planet's surface, which is almost perpetually shrouded in darkness and blanketed with snowstorms, the Doctor and Clara discover the tiny village of Christmas, which is under the influence of a truth field. The village's central feature is a clocktower from which the signal, and the truth field, is emanating... and when the Doctor takes a closer look, he finds himself reunited with the crack in time, through which the message is being broadcast... from Gallifrey.