Not quite as creepy as "Hide", but pretty good.
So thoughts...
- Good and creepy on the atmospherics and things coming out of the walls.
- I wish they had kept in the reference to Harry's other grandfather. Would have loved it if the Doctor had made the connection with Harry Sullivan.
- Everyone lives in the end of this one. Did they think it would get too depressing for the season if everyone died all the time?
- Is there a deliberate parallel between the girl being kept hidden in the tower for 70 years and whatever is in the vault that the Doctor has kept locked up for 70 years?
- Whatever is in the vault plays the piano and eats Mexican.
- It's safe for the Doctor to enter the vault.
- Nardol doesn't view what is in the vault the same way as the Doctor does.
- Is the vault keeping us safe from it, or the other way round?