“Are you okay?”
“Good. There would be something very wrong if you were.”
Well, it’s always interesting when the “no, it can’t be...” fan theories prove right. I hesitate to look at fan reactions at the best of times, but at the cliffhanger of a two-parter with a bombshell like that...
So Missy (aka, if she isn’t lying again, the Mistress) is about to drop an army of Cybermen on roughly modern London, with the memories of the dead collected from across time and space, particularly those with a bone to pick with the Doctor. Not that she wants to kill him, because he’s her boyfriend. (And they could be the parents of a new Gallifreyan race... though I suspect the Doctor wouldn’t be terribly keen.)
The “Clara doesn’t exist” stuff may well be from next week. She does various scary-looking things here which feed into it. The Doctor forgiving and helping her was lovely and touching, by the by.
Cybermen invaded by appearing to be ghosts before, but actually being ghosts this time...
Look both ways before crossing the road, everyone. The Doctor really doesn’t like saving people from being run over.