After the loss of Amy and Rory, the Doctor, depressed, hides himself on top of a cloud in Victorian England’s London, vowing never to save the world again. Meanwhile, the “Great Intelligence”, a form of “memory snow” which can mirror the thoughts of anything around it, hatches a plot to create an army of ice people. While Strax drives the reluctant Doctor around, they both run into Clara, a barmaid. The Doctor refuses to investigate the snowmen and returns to semi-seclusion in the TARDIS, which is parked in a cloud above London, accessible from ground level via a staircase. By following the Doctor, Clara finds the TARDIS, but leaves, without talking to the Doctor. However, Clara soon returns to her regular job as a governess and learns of an imminent danger to her wards and possibly all of humanity. She turns to the Doctor for help and, motivated through Clara’s charm and an interesting set of coincidences, the Doctor takes action. Together with Madame Vastra, Jenny Flint, and Strax, the Doctor and Clara are able to defeat the Great Intelligence and its human servant, Doctor Simeon, using ingenuity and the pure energy of a family crying on Christmas Eve. In the process, the Doctor regains his enthusiasm for adventure and heroism, deciding to take Clara on as his companion. However, before the enemies are defeated Clara is thrown off the edge of a cloud and falls to her death, though the Doctor was sure she would survive. At the end of the episode, the Doctor discovers Clara’s full name – Clara Oswin Oswald – and comes to the realization that Clara is the same person as Oswin Oswald from the episode “Asylum of the Daleks“. He concludes that she is more than likely still alive in some other place and time and leaves in the newly-redesigned TARDIS to find her.