It's Christmas Eve in 1851 and Cybermen stalk the snow of Victorian London, in this special Christmas edition of Russell T Davies's Bafta Award-winning time-travelling drama.

When the Doctor arrives and starts to investigate a spate of mysterious deaths, he's surprised to meet another Doctor, and soon the two must combine forces to defeat the ruthless Miss Hartigan. But are two Doctors enough to stop the rise of the CyberKing?