Christmas Eve, 1892, and the falling snow is the stuff of fairytales. When the fairytale becomes a nightmare and a chilling menace threatens Earth, an unorthodox young governess, Clara, calls on the Doctor for help. But the Doctor is in mourning, reclusive and determined not to engage in the problems of the universe. As old friends return, will the Doctor really abandon humankind, or will he fight to save the world and Christmas from the icy clutches of this mysterious menace?

Agatha Christie's 10-day disappearance in 1926 may have been the result of amnesia, a nervous breakdown, or a giant alien wasp.

When an old cinema re-opens, past horrors emerge to stalk the streets of Cardiff. And as bodies are found, somewhere between life and death, Torchwood must act fast. Who are the Night Travellers? And how can Torchwood capture these mysterious killers?

When the Doctor investigates a spate of mysterious deaths, he's surprised to meet another Doctor. The two must combine forces to defeat a human ally to the Cybermen. But are two Doctors enough to stop the rise of the CyberKing?

Can Rose trust a man with a new face? As the newly regenerated Doctor drifts in and out of consciousness, Christmas becomes a time of terror on planet Earth when the whole of mankind falls under the shadow of the sinister alien Sycorax.

The Doctors embark on their greatest adventure across space and time in this 50th Anniversary Special.

Christmas Eve 1892 and a chilling menace threatens humankind - but with the Doctor in mourning, it takes old friends and an unorthodox young governess to get him fighting to save the world again.