Almost flawless.

Steven Moffat's episodes to date have been so highly rated I was beginning to think that my expectations were impossibly high and doomed to disappointment, especially when I realised that this is the season's 'Love & Monsters'/'The Long Game' Doctor-lite episode. I was wrong. If you're going to give David Tennant and Freema Agyeman a week off *this* is the way to do it. This episode just goes to show that a great concept and great writing can make the (partial) absence of your regular cast into a virtue. I'm sure some will dislike it simply for being so light on the regular characters--effectively an anthology short story--but for me the execution makes this an almost complete success and a very strong follow-up to a very strong two-parter. While it focuses on supporting characters it retains all the genre-bending imagination that makes Doctor Who such a flexible format for a series (albeit one that's not always fully exploited).

There are so many lovely games played with time in this episode, all deeply implausible and yet somehow giving the impression of intricate clockwork precision. The device of the Doctor's foreknowledge is one packed to the brim with sense-of-wonder, even if it's just a particularly clever spin on the old Bill & Ted "remember to leave the key under the plant pot" shtick. The way that it comes together from the point of view of Sally Sparrow, the outsider, only adds to the air of mystery and wonder, and yet by the end of the episode we have a very clear idea of what went on. We're allowed to peek behind the curtain without spoiling our enjoyment of the illusion. No doubt (like elements of Moffat's 'The Girl in the Fireplace') the premise will soon be shown to be full of holes, but crucially that's not the impression left during the episode. (Of course, in reality the Doctor couldn't possibly have received such an accurate transcript that he knew how long to pause between his responses, but he's a Time Lord so I'll cut him some slack.) Coming hot on the heels of Paul Cornell's two-parter this episode has the (perhaps inadvertent) quality of cementing the Doctor's Machiavellian characteristics.

The aliens, with their quantum nature, are a second inventive high concept--which seems generous given that several episodes this season haven't had any. Here the script pulls off that perfect Lovecraftian trick of blending mythology and horror with the veneer of Science Fiction to create a sense of Deep Time and ancient horror. They're a fantastically atmospheric creation, and the scenes in which they move in a staccato series of frozen poses are really scary, in a way that TV seldom is. They're scary in their very concept, evoking a shiver of dread rather than just the usual fear of being eaten. I find myself referencing Sapphire and Steel too often when talking about horror-SF, but this is exactly the kind of imaginative corner-of-the-eye horror that was the stock in trade of that series.

The other great strength of the episode is that the supporting characters are written and played so sympathetically. By the end of the episode it's hard to escape the feeling that Sally would make a great companion so likeable is she, but Kathy and Ben are no less well-rounded despite far less screen time. The script has compassion for their plight, and finds the beauty as well as the tragedy in their lives. It's these character moments, never caricatured, and never forced, that really make the story come alive.

My main criticism of this episode is that the logic of the aliens' movement is almost impossible to render accurately when staging a scene with actors and so there are a few hiccups in when the statues move and when they don't towards the end. Also you'd think the pair would have hit upon the idea that they take it in turns to blink, which would have helped (as long as they kept all the statues in the same field of vision). And lastly the Scary Statues Montage at the end feels a tad bolted-on: the idea has already wormed its way into your subconscious by this stage and the epilogue is superfluous. These minor niggles aside, this is an excellent episode.