Writing this up a little late, as we ended up extremely busy this weekend & at the beginning of the week, so I'm sure some of the things I thought of to say at the time we watched it have vanished from my head. Oh well.
SPOILERS AHEAD! Hover mouse over text to read, or read on entry page:
Another recurring thing this episode was about "missing the headline" - commenting on/talking about one thing when another thing is more significant. So I'm pretty sure there'll be pay off to that next episode. There's a scene from the trailer for the finale that we haven't had yet and I reckon either what Clara was saying in it was total misdirection or that fits in here with missing the headline in her opening conversation with Danny (despite her insistence she's started with the headline). Being vague because J doesn't watch trailers and doesn't want spoiled for it.
We did find out quite a lot of what's going on here though - Missy == the Master as speculated. And she's taking backups of dead people and convincing them to delete their emotions prior to re-downloading them into cyberman bodies inhabited by corpses. There's a lot of resonance here to the opening episode with Clara (modern-Clara that is) - The Bells of Saint John (post) - can't claim credit for thinking of it myself, I read someone else's hope that the current story wouldn't save Danny whilst writing off all the other dead minds in the same way that first story saved Clara but not all the rest. But definite reminders of that episode now I think about it. I'm presuming that Missy is the woman who gave Clara the phone number that gets her in touch with the Doctor. There are also minds that are uploaded in some fashion, with dead bodies left behind. Tweaking of the emotions once the mind is digitised too - I remember sliders to move emotion/intelligence etc up and down. I'm not suggesting a direct link of any sort here, just that there's a lot of resonance and it feels to me like we're maybe supposed to be reminded.
Definitely looking foward to the next episode and finding out the answer to what's going on! :)