Now there's a two-parter thoroughly rescued by its second part - at last, the first high 9/borderline 10 of the season. Those plot details were a little easy to work out after all (mmm, smuggy-smug-smug) but the execution was first rate. Particularly good was the sub-story around Donna's virtual world, which could have carried an episode on its own.
Amusingly, this side of the episode seemed to be all about television - amusingly, because of it being set in a library. The open acknowledgement of the cuts from scene to scene, of course, and the computer girl being pressed into a secondary role as a parody of the younger viewers, not to mention the direct address to the viewer from inside the virtual world at the end. This does slightly emphasise, if not actually raise, the question of why none of the episode was about books. Or at least, about reading. A library would seem to be the obvious setting in which to explore that theme.
Even this, the last mysterious thing about the two-parter, is kind of addressed by the explanation of why the Vashta Nerada have turned predatory. It's their vengeance for the destruction of their habitat - the pulping of enough trees to layer an entire planet with books. So this part of the episode is about books, only here they're not "the best weapons you can have" (qv Tooth and Claw) - not books as a means of transmitting knowledge - but rather books as objects, as things made out of wood pulp. And to rub it in, they're completely surplus to requirements because the Library computer has the whole lot stored electronically, with the added advantage that anyone who doesn't mind being reduced to digital information can experience them all directly. (And you'd assume there'd be some way in the 51st century of achieving the same effect with a headset and a comfy chair. Make the mainframe a bit bigger, replace the planetwide reading rooms with a modest-sized building filled with comfy chairs and you'd be able to have the tourist attraction and the forest.)
So there's actually a crafty eco-message hiding underneath the surface of this story, although it's not dwelt on at all and one assumes the junior members of the audience will have been too preoccupied with the zombie spacemen and Miss Evangelista's freaky distorted face to have spotted it anyway. Possibly just as well - thought-provoking it may be, but is "books = bad" (or even "books = irrelevant when you've got films") really a message you want to send to the nation's kids when literacy is such a hot issue in the tabloids?
(There is a whole other level of philosophical debate lurking behind this, whereby we see characters being uploaded into the Library mainframe's virtual environment and equate them with the books the mainframe was designed to deal with - i.e. "flesh = irrelevant when you've got mind" - but that'd probably be even less palatable to the general audience.)
Other considerations. Colin Salmon was just fantastic as Dr Moon ("...and then you forgot!") - it'd be nice to think he might pop up again in Who in another role. (Come to think of it, he'd make a great Eleventh Doctor, but then again I assume that, based on RTD's casting of Dr Eccles and David Tennant, the smart money would be on the Grand Moff casting someone he's worked with before - Jack Davenport or James Nesbitt would seem the obvious front-runners. But I massively digress.)
Quite surprising that Lux's blatantly symbolic surname didn't play any part in the story at all, not even as a side joke.
I know what I said last week about it being too early to spot patterns in the way Moffat writes, but oh look - our heroes escape the monsters by blasting a neat square hole in a side wall, and at the end "just this once" (again) everybody lives. Even if they died (so Moffat can do the obvious thing of killing off River Song and bring her back).
Which brings us onto the plot hole (I think there was only the one) - how did Miss Evangelista (and the other victims, at the end) get inside the mainframe? I don't recall any suggestion that the Library was scanning her the whole time, or reading the neural relay in her collar, or that anyone loaded her into the mainframe (as if anyone would have had the chance).
And I can't not mention the whole issue of the Doctor's relationship with River Song, which was delightful and has the potential for a lot of very interesting development further down the line. Always assuming Alex Kingston is up for a few repeat appearances, of course. (And so continues Steven Moffat's "Get Over Rose" agenda! First Madame de Pompadour...)
Next week seems to be another take on disaster movies. I just want to tell you both: Good luck, we're all counting on you.
Also this week: life continues to punish us for owning a car, with the new Toyota fresh from one expensive servicing and straight back in for a week and a half to have its head gasket replaced (there's probably a crafty eco-message hidden in there somewhere too); and congratulations to The Lovely Jo who won two bronze medals at a taekwon-do competition on Saturday, and who's just celebrated her birthday.