I loved this episode. I thought it was the best start to a season for a long time, maybe since Rose. Peter Capaldi was fantastic as usual, Pearl Mackie made Bill really likeable and believable, and even Matt Lucas pulled off a pretty good performance as Nardole.
Steven Moffat’s script was written perfectly, with every line of dialogue being amazing and immaculately judged. The parallels between this and An Unearthly Child made me love it even more.
I think that John Simm’s Master is in the vault. At the end of Last of the Time Lords, the Doctor says that he needs someone to care for. If it’s the Master in the vault, then the Doctor is caring for him…