Doctor Who is often at its best when it focuses on just one thing. There’s a Rutan in a lighthouse. Who created the Daleks? Don’t blink, blink and you’re dead. Trying to juggle too many different ideas, concepts, points of focus can easily lead to muddle, especially when you’re trying to deliver a movie-of-the-week in 45 minutes.

Sometimes an episode can suffer from being over-ambitious and yet the parts which work work so well that I’m prepared to forgive a bit of muddle. School Reunion never does anything interesting with its alien invasion plot beyond a bit of amusing undercover work from the Doctor in the first five minutes. But the return of Sarah Jane and K9 and the amazing meeting-of-companions past and present means that the underdeveloped melodrama never gets in the way of the relationship story which delivers handily.

Writer Chris Chibnall’s best script for Doctor Who is easily 42, which follows the principle of Keep It Simple Stupid. By contrast, the Silurian two-parter has barely enough material for 60 minutes, let alone 90. And Dinosaurs on a Spaceship is an obvious first-draft with no care or time taken to smooth over the bumps and properly bed-in the plot points (despite Moffat’s claims in Doctor Who Magazine that the script was “perfect” as delivered). How would The Power of Three measure-up given that it was trying to balance an alien invasion plot with a Ponds-eye view of The Doctor?

By and large, it worked very well indeed.

The sudden arrival on Earth of countless identical smooth black cubes is a delightful and arresting image, which works extremely well as a point of focus, providing The Doctor, Rory, Amy and not forgetting diligent Brian, with a deep mystery to explore, providing time for The Doctor’s impact on the Ponds’ lives to be examined. As well as including the traditional first-person narration by a shortly-departing companion, the story is full of incidental pleasures – The Doctor’s demented need to fill time by playing keepy-uppy, doing the hoovering and painting any available fences; an RTD-style series of celebrity cameos; the return of UNIT, now re-oriented (“science leads”) and led by daughter-of-the-Brig Kate Stewart played by bloody Jemma Redgrave; and the now apparently obligatory side-story, this time involving Zygons and Henry VIII.

All this time, we get only a couple of hints at the cubes’ necessarily malevolent nature and this too is a dangerous game. The longer you leave it, the more you spin out the suspense, the more jaw-droppingly amazing must the reveal be when it finally comes. Chibnall again plays it clever here by initially making the actions of the cubes when they come to life bewilderingly inconsistent, but when they do strike, it’s fierce and hard.

It’s really only in the last ten minutes that the careful balancing of timing and theme slips through the story’s grasp. While it’s an enormous pleasure to see Steven Berkoff snarling his way through the lines, Shakri’s plan and motivations were pretty standard-issue, and The Doctor’s solution seemed to amount to little more than a bit of sonic-ing. Here’s also where, in his zeal to build up the excitement and whack up the stakes, Chibnall hugely over-reaches himself. As soon as you announce that around a third of the Earth’s population has suffered fatal heart attacks, any half-awake viewer is going to recognise that a reset switch is about to be thrown. And while I’m grateful that a) we didn’t actually rewind time and b) the solution was properly bedded-in to the story and not grafted-on at the last minute, the timing is way, way off. Even given that the cubes, which are designed to find live, beating hearts and administer a fatal shock, can be reprogrammed with a flick of the sonic to instead find only those hearts which have already been stopped and administer a shock sufficient to get them going again, The Doctor still has only  something like two minutes to zap the victims before permanent brain damage is inflicted. Not the many minutes of Berkoffing which we actually got. And that’s generously drawing a veil over the fact that you can’t shock a non-beating heart back into life anyway, only correct the rhythm of a heart which is not beating properly. And while I enjoyed the sight of The Doctor struggling through with one heart out of action, I was frustrated at how quickly and easily this was resolved. Surely, if anyone is going to defibrillate The Doctor in a hospital, it should be medically-trained Rory?

So, if the climax was a bit skimpy, the Pond/Doctor story generally made up for it, with Brian’s final speech sending the Ponds back to the TARDIS I thought particularly effective. It’s an essentially unbreakable rule of scriptwriting physics that the more screen-time you give to your personal drama, the less you have available for your alien-invasion plot, and it’s to Chris Chibnall’s credit that he balanced both demands as well as he did for as long as he did.

Elsewhere, the production team is not tested to breaking point, but ably rises to the occasion. The make-up job on the two creepy orderlies is fine (if a bit reminiscent of The Empty Child), Douglas Mackinnon’s camera consistently frames the story in interesting ways and Karen Gillan and Arthur Darvill prepare to send the Ponds off  to their final reward in fine style.

For the first half-hour, I honestly thought this was going to be my favourite of the season so far, earning four-and-a-half or even five stars until the last ten minutes, but that slightly limp resolution sees The Power of Three stuck on four, roughly even with Asylum and Mercy but still a tremendous improvement on the dreadfully clumsy Dinosaurs on a Spaceship.

4 out of 5 stars
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