While I’m not planning to go into a lot of plot details, it’s likely that the random mutterings that follow will reveal some things you might prefer not to know if you haven’t seen the episode yet, so in my usual way, I’ll include this warning:
No, really. Big fat honking spoilers. You have been warned.
Any episode that begins with the Doctor’s voice saying
Space: the final frontier…
before skipping all the bold infinitive splitting and going on to how space isn’t all that nice and wants to kill you, is clearly trying to set up something. And so it does…
Despite Nardole’s protests and warnings about “our friend in the vault” knowing when the Doctor is away, the Doctor takes Bill (and an unwilling Nardole) to a space station that’s transmitting a distress signal (“my theme tune”).
And the station is indeed in distress. Out of the original forty crew, only four remain alive, the rest shuffling about in full-on zombie mode, though without any suggestion that it’s Brains they’re after. After much confusion and near-suffocation, the Doctor and his friends are rescued by the remaining crew who they’ve come to rescue.
Bill is slightly surprised that one of the crew is a blue-skinned alien. He notices her reaction and says
Great. We’ve rescued a racist 🤣
which flummoxes Bill a bit.
Much of the usual running through actual corridors follows before the Doctor pulls a solution of of the hat he’s not currently wearing and rescues the two remaining crew members.
But it’s not all as easy as that. Having given Bill his space helmet to save her life, he’d been exposed to vacuum, which had temporarily cost him his sight. Look, I did warn you about spoilers, didn’t I? Anyway, he reassures everyone that this won’t be a problem, lots of medical technology on the Tardis, that’ll sort it out, don’t worry.
Well, they get back to the Tardis, some medical thingumyness is done and his eyes stop having that whiteout effect, and so all is well, right?
Well, as far as Bill knows, anyway. It’s only after she’s left the office that he admits to Nardole that he’s still blind…
Will he be blind for the rest of the series? Will something clever be done next week? Will his meeting with the Pope go well? And what’s Missy doing? Some of this may be revealed…
 Not that there’s anything wrong with splitting infinitives, unless you’re a 19th century nitwit who thinks English should conform to Latin grammar
 At this point, most people have a very good idea of who’s in there. It would be great fun to find out we’re wrong, which wouldn’t surprise me at all, knowing the devious mind of Mr Moffat. Though there again, maybe the surprise is that it’s exactly who we’re expecting, which would be quite unexpected.
 This may be a recycled old beer advert that just popped up from the depths of my memory