Parts: 1 (60-minute)
Writer: Russell T Davies
Airdate: 25 December 2008
Production Code: n/a

Doctor: tenth
Companion: none

Creature Feature: Cybermen

Story: The Doctor is charmed upon landing in a snowy Victorian marketplace on Christmas Eve, 1851, but the idyllic wintry setting is soon shattered by someone screaming for... him. Intrigued, the Doctor races to help the damsel in distress, only to find that she's calling for a different Doctor... who shows up carrying a sonic screwdriver, and claiming to be a Time Lord. The Doctor, astonished, realizes that he must have crossed his own timestream, and has encountered a future incarnation — but one who, for some mysterious reason, has absolutely no idea who he is.

His timing seems fortunate, for the other Doctor is battling a Cybershade, proof positive that Victorian London has been invaded by the Cybermen. But where they're hiding, and what they want, neither Doctor knows. To find out, the Doctor and his counterpart's companion Rosita will have to restore the next Doctor's memory, before the Cybermen activate their plans for London.