Jamie Mathieson’s first two scripts for the show – Mummy on the Orient Express and Flatline attracted near-universal praise, including from this blog, so expectations were high for his return in series ten. Were they met? Ah… nearly.

The set-up is largely great. Putting the Doctor and his – still very new – companion at risk of a terrible death in the icy vacuum of space is a great idea. The David Tennant episode 42, and in particular the sight of Martha Jones drifting off into nothing, is one of the very few things keeping me optimistic about Chris Chibnall’s forthcoming takeover of the programme. And who doesn’t like seeing Capaldi wandering around a deserted base making macabre quips, even if that kind of thing has been happening a lot lately.

The teaser is also very compelling, with the zombie colleague offing the newly-engaged couple and – look! – Nardole’s allowed to come. So what’s the problem? Well, there are too. One is a science niggle, but it’s such an important plot point that I can’t permit it to go unchallenged. For, I suspect practical production reasons, the cast don’t wear their helmets most of the time, but instead have a forcefield around their heads which keeps the air in. Thus even though the inside of the station is a vacuum, they can breathe normally.

But suddenly when they have to go outside the station, proper helmets are required. But either the station is deprived of air or it isn’t. As soon as there’s any opportunity, the pressure will equalise. You can’t maintain a thin atmosphere like on a small planet. And thus, either the forcefield can create an air-tight seal or it can’t. There’s just no way that the vacuum inside the station is more vacuum-y than the vacuum outside the station.

So, this rather takes the shine off the generally terrifying ordeal of the station inhabitants (as usually, poorly-differentiated, although the blue one is a nice sources of gags about racism, although played by a white actor I believe) and horrendous sacrifice – more on that later. The other, far bigger problem is that the episode is not so much rushed as absolutely stuffed. Whereas several recent episodes have had about thirty minutes of story and ten-fifteen minutes of running around and quipping (The Witch’s Familiar being the most egregious recent example) this could have certainly made a 60 minute special and is probably only one subplot away from being a two-parter.

So, when the Doctor’s blindness is easily fixed back at base, I’m intensely frustrated that such a brilliant idea wasn’t given time enough to be really developed and explored. Except of course – they aren’t done with that idea yet, are they! A lovely final twist to a thrilling and very well-executed episode.

I’ll quickly note that I don’t regard the profiteering algorithm as another automatic system gone awry for the simple reason that the algorithm was programmed by heartlessly profiteering bad-guys, so it’s not a benevolent system which becomes accidentally fatal, it’s a ruthless system doing exactly what it was intended to do.

4 ½ stars. Hurrah.

So... what did I think of Thin Ice?
So... what did I think of Extremis?