The new clip sees Madame Vastra and her companions investigate a Victorian murder. But where is the Doctor?

> Watch the previous prequel, ‘The Great Detective’.

Airing on Tuesday 25 December at 5.15pm on BBC One, ‘The Snowmen’ is set on Christmas Eve 1892 and the falling snow is the stuff of fairy-tales. When the fairy-tale 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.

Watch the prequel…

> Buy Series 7 Part 1 on DVD on Amazon.

Are you looking forward to the Christmas special? Let us know below…