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. 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.