John continues in his herculean effort to review EVERY screen story for our favourite Time Lord...

“Three. That's the magic number.” So claimed legendary rappers De La Soul in the Daisy Age of 1989. And it would seem that everyone's favourite Time Lord agrees too. Back in 1972, three incarnations of The Doctor were needed to defeat the awesome might of Time Lord pioneer Omega and his lumbering jellies. Three is normally the number of seconds afforded by gun-totin' maniacs such as The Brigade Leader, before the trigger is pulled. And in Earth's future, it seems that only three Daleks are needed to create fear and terror throughout the land, while hiding in a cramped metal box.

The Power Of Three extended to the latest triple whammy shenanigans in Doctor Who. Now this doesn't relate to a killer phone network, nor does it relate to a clandestine Time Lord code – in fact, it refers to the penultimate hurrah of the ongoing TARDIS trio. The Power Of Three revolves around the evergreen team of The Doctor, Amy and Rory – or to be more precise, it's the traditional palate cleanser before the real trials begin. Whether or not this is Moffat's answer to Black Orchid is, at the time of writing, a mystery that's up for grabs. Amy and Rory don't exactly stand around eating plates of stale food, Amy doesn't sip cocktails in her bath, and there's no embarrassing dancing at their celebratory anniversary bash – or at least Adric's definition of dancing, which reads as shuffling awkwardly from side to side like a pained ostrich with a gammy foot.

"Even when the cubes start meaning business, it takes a whole year – officially, this is the laziest world domination plan ever devised."

Instead, they're faithfully assisting The Doctor in solving the mystery of the sudden appearance of several cubes all over the world. Before you ask, these are not the sorts of cubes that you can enter to bounce a rubber ball into a futuristic bucket before the beady eyes of Philip Schofield. They're small, dull blue boxes that kind of look like the sort of thing you could buy for about £1.99 in a seaside tourist resort shop. “Arrrrhhh, these 'ere cubes are emblazoned with our local flag, so they'll be worth millions in 10 years time.” As far as invasions go, it's not the most thrilling of threats. At first, people seem to think that they're enigmatic fads. Even familiar TV people are jumping on the bandwagon, including Baron Von Sugar and his hatchet-faced lackeys, and that clever physicist guy who looks a bit like Thelma from Whatever Happened To The Likely Lads. Heck, there's even lots of Twitter accounts devoted to the mysterious cubes, causing The Doctor to crush his already gritted teeth into crumbs.

Even when the cubes start meaning business, it takes a whole year – officially, this is the laziest world domination plan ever devised. It turns out that the cubes are dishing out presents of cardiac arrests to a third of the world's population – they are the work of intergalactic pest controllers, the Shakri, Gallifreyan legends by all accounts, but in reality, pretty useless. Not only do the cubes take all of a year to make a scrap of difference, the deadly effects are also easily reversed in a matter of seconds. Simply use your ship's computer to restore the dead humans back to life, and hey presto! You officially have the galaxy's most useless plan for mass genocide. Legendary pest controllers, my arse – the Shakri even look rubbish, a sort of cross between a talking rugby ball and a bad Star Trek alien. A good performance from an unrecognisable Steven Berkoff, but it's a pity that this great actor couldn't have had something more substantial to do.

Which is probably why the whole cube fad subplot is relegated to the sidelines. The Power Of Three is more of a character piece, along the lines of The Lodger. Like the 2010 story, if you try and rate The Power Of Three on drama alone, you'll come away feeling short-changed. On the plus side, there's a pleasing throwback to the Russell T. Davies era. Not only do we have celebrity cameos, but scrolling news tickertape reports, with ominous close-ups of solemn newsreaders' frowning, contorted visages. It's like Rusty had never left the executive producer's seat – you half expect David Tennant to leap out of the TARDIS to greet Amy and Rory with an unrestrained holler of “Bwwilliant!”

Even better is the return of UNIT, now helmed by Kate (Lethbridge-)Stewart, daughter of the late, great Brigadier Alistair Lethbridge-Stewart. If you've ever checked out the 1995 spin-off Downtime, then you'll be happy to know that writer Chris Chibnall has stuck with established events, since the straight-to-video release introduced Kate. She's played by a different actress this time around, but Jemma Redgrave plays her very well indeed, so much so that I'd hope for her to make future regular appearances alongside Son of Sergeant Benton and Nephew of Mike Yates.

"Approach The Power Of Three as a whimsical character piece, however, and there's actually lots to enjoy. It's one of the last chances to savour the endearing triple act of The Doctor, Amy and Rory. It's very rare for companions to get this much depth of storytelling, and by spreading the story over a year, we get a bit more insight into the minds of the TARDIS crew."

In dramatic terms though, The Power Of Three is also similar to the odd Davies-era story in that the resolution of the story has the sophistication of Sooty waving his magic wand around while Matthew Corbett, Sooty and Sweep chant “Izzy wizzy, let's get busy”. It's a shame that the resolution to this problem is so uninspired and lacking in originality. Like Last Of The Time Lords , the resolution's a massive cop-out, and is more than a bit annoying. There's no real explanation either as to who the surgical Oak And Quill-esque alien goons are either, and yet again this season, The Power Of Three is not exactly a story to be watched from behind the sofa. Hopefully, the Weeping Angels half-season finale will redress the balance a bit, but generally, Doctor Who's main Unique Selling Point of terrifying kids has been lost of late.

Approach The Power Of Three as a whimsical character piece, however, and there's actually lots to enjoy. It's one of the last chances to savour the endearing triple act of The Doctor, Amy and Rory. It's very rare for companions to get this much depth of storytelling, and by spreading the story over a year, we get a bit more insight into the minds of the TARDIS crew. Amy and Rory are faced with the choice of actually growing up and settling down into their domestic lives, or carrying on their flights of fancy with The Doctor. The big question is, Can the two lifestyles ever run parallel? Amy now has a job as a travel writer (presumably not for Outer Space Spas Weekly), while Rory is looking to work full time at his hospital. As a result, they wonder how another trip in the TARDIS can slot into their everyday lives. Even an anniversary party proves to be unorthodox, after The Doctor's own unique brand of anniversary gift takes them away from the shindig for a bit longer than they had anticipated (thanks to those pesky Zygons). “Doesn't feel like real life gets much of a look-in,” muses Rory early on in the episode.

By contrast, The Doctor, forever a man on the run, is struggling to adapt to mundane Earth life after agreeing to stick around to help solve the mystery of the cubes. Only four days in and he's bored out of his skull, impatient and irritable (“Patience is for wimps!” he bellows at one point). In a short space of time, he amuses himself by doing odd jobs for Rory and Amy, and displaying considerable football prowess – seriously, why was this man never considered for England's hapless football tournament campaign this year? The Doctor's thirst for knowledge and action can never sit with normal Earth lifestyles – no wonder his earlier incarnation was frequently in a foul temper during the early 1970s. The throwback to the RTD days does highlight how much has changed with the new kid on the block, though. Whereas the Tenth Doctor slotted in more easily into contemporary Earth life (enjoying Christmas dinner with Rose et al, taking Rose to see her mum on many occasions), his successor cannot relate at all. Even something as ordinary as a job is treated with bewilderment by the Eleventh Doctor. “The universe is awaiting, but you have a little job to do,” he says to Rory.

"Both scenes contain some superb dialogue – one thing I've noticed while reviewing Doctor Who stories is the writers' real talent for writing cracking lines."

The centrepiece of The Doctor's thirst for travelling the universe is that lovely two-hander speech between him and Amy. After Amy says that the TARDIS travels feel like “running away”, The Doctor replies that he's doing the opposite. “There is so much...so much to see, Amy, because it goes so fast. I'm not running away from things, I am running to them – before they flare and fade forever”. That Doctor, eh? He has a better grasp of what life's all about than us mortal humans – make the most of opportunities that come your way and grab them with both hands.

The same scene is also notable for addressing The Doctor's constant returning trips to Amy and Rory. Amy asks him why he keeps coming back, to which The Doctor responds that she was the first – “The first face this face saw – and you were seared onto my hearts, Amelia Pond. You always will be – I'm running to you and Rory before you fade from me.” Quite how this sets things up for the finale episode remains a mystery at the time of writing – judging from both this scene and the two-hander between The Doctor and Brian (“Some died. Not them, Brian. Never them”), it could be a case of stockpiling hankies for next week's thrilling instalment.

Both scenes contain some superb dialogue – one thing I've noticed while reviewing Doctor Who stories is the writers' real talent for writing cracking lines. I'd give anything to be able to write dialogue like that. It's all-encompassing, from moving and warm-hearted through to witty and funny (“My! A kiss from a Lethbridge-Stewart, that's new!”), and demonstrates Chris Chibnall's writing skills to the max. It's leaps and bounds ahead of earlier Chibnall efforts such as 42 and The Hungry Earth two-parter. As ever, the main cast bring excellent performances to the table. Matt Smith gels perfectly with Karen Gillan and Arthur Darvill – the latest TARDIS crew has become one of the enduring line-ups, following in the footsteps of The Second Doctor/Jamie/Zoe, The Third Doctor/Jo and The Fourth Doctor/Sarah. Compare Amy's and Rory's latest adventures with their earlier ones, and they too, have gone from shaky starts through to being firm favourites with the viewers and fans. It's also a shame that this is likely to be the last adventure to feature Mark Williams as Brian, since he's proven to be a funny, likeable presence, almost along the lines of good old Wilf. Brian's a lot smarter than you might think, revealing that Amy and Rory should go and do some good in the world – recalling how Wilf often urged Donna to go and see the stars in that once-in-a-lifetime opportunity. “Go save every world you can find. Who else has that chance?”

"As ever, the main cast bring excellent performances to the table. Matt Smith gels perfectly with Karen Gillan and Arthur Darvill – the latest TARDIS crew has become one of the enduring line-ups, following in the footsteps of The Second Doctor/Jamie/Zoe, The Third Doctor/Jo and The Fourth Doctor/Sarah."

From a production point of view, the action's handled well by a returning Douglas MacKinnon (who had last helmed The Sontaran Stratagem/The Poison Sky ). The outer space scenes are well shot, and the same goes for the individual cubes – a simple idea, but well executed. The passing of time is done well, to the point where there's a clever, meaty word "June" sizzling on the party barbecue. Just cover your ears when Merry Xmas Everybody or The Birdie Song start playing.

The Power Of Three requires the right frame of mind for maximum enjoyment. Take it as a straight-ahead, no-nonsense drama, and you'll probably end up walking away swearing under your breath. Take it as a well-written and well-acted character piece, and you'll probably love it to pieces.

John Bensalhia limbered up for his Shadowlocked writing with a full four-series review of Blake's 7, and writes professionally and recreationally all over the web. Check out his portfolio of work here. His Twitter feed is @JohnBensalhia.

Check out John's previous Doctor Who review, A Town Called Mercy

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