The Zygon Inversion written by Peter Harness & Steven Moffat and directed by Daniel Nettheim

This story in a nutshell: Ten minutes of gold surrounded by a lot of problems...

Indefinable: Despite the fact that I will suggest elsewhere that Peter Capaldi gives is most assured and memorable performance in The Zygon Inversion (which he does but it is contained within a gobsmacking ten minute acting set piece), he does still face some of the smug quirks that have held him back the rest of the year. A terrible American accent, walking away from a lane wreck without batting an eyelid and brandishing those hideous sonic sunglasses again. Less of that please because the best of what we see here is the best that the Doctor has ever been. And 51 years after his first reveal that is an extraordinary statement to make. It's astonishing that we have spent the last season and half with Capaldi and Coleman and yet this material sheds new light on what they can deliver, performance wise, in a very refreshing way. Trust the Doctor to even make his conflict deterrents over complicated - four functions? Capaldi must have salivated when he read the second half of this script. Even his staunchest of critics this year who have suggested that he hasn't been offered material worthy of his talents have to shut the hole in their faces. People like me. The Doctor's reaction to the futility of war and the need for conversation over adversity is so striking and raw, I don't think the point has been clarified this perfectly in the past five decades. It boils away all the quirks and gets to the heart of what the Doctor is all about in a fashion so riveting (it's essentially all down to Capaldi) that I can't imagine it ever being bettered.

Impossible Girl: Both something of a missed opportunity AND a fascinating turn by Jenna Coleman. Both of the regulars are given rare opportunities in this episode, far out of their comfort zones as the Doctor and Clara. What baffles me is that if Jenna Coleman can be this riveting to watch...why is she stuck playing the ceaselessly vanilla (if likeable) Clara? Imagine a darker, less perfect version of Clara in the Bonnie mould (kind of what we got in Dark Water but not just when she is in the throes of depression) full time? How much more interesting would that have been. Bonnie is cold, calculating, intelligent, ruthless, thoughtful...and Coleman runs with it. It's quite a feat because evil doppelgangers can bring the worst out in actors and yet she resists the chance to descend into moustache twirling villainy and instead creates a fully formed character that is so distinct from Clara that it exposes her versatility as an actress better than her usual role ever has. As a showcase for Coleman, this is extraordinary. As an example of what a missed opportunity Clara has been, it's quite a painful watch. I also question the psychological intensity of the Clara/Bonnie scenes which are mere pin pricks when they should have gone for the jugular and been much more probing and disturbing. I might have tackled Clara's alleged bisexuality in these scenes, I would have had Bonnie stop her heart and enhance that feeling of claustrophobia and I would have used the exchanges as a chance to tell us more about Bonnie as a character. The idea is sound, they just don't do much of interest with it.

Sparkling Dialogue: 'Why can't I just live?' Bravo for that line. Bravo for giving the non-violent immigrants a sympathetic voice.

The entire speech by the Doctor...which would take far too long to quote. Rather than reading it here just go and watch it again. The words on the page cannot do justice to the skill in which they are brought to life by Capaldi.

The Good:

* One of my major complaints about The Zygon Invasion was that the overall view of the Zygon immigrants was very one sided with only the extremists being represented and behaving in an appalling way. This is immediately rectified in Inversion and I really appreciated the scenes of the peaceful Zygon being forced to metamorphose and expose himself to the rest of humanity. It is a not-very-subtle way of showing how the few make life extremely uncomfortable for the many. Just because one foreigner is shown to be a terrorist, it doesn't automatically mean that everybody with the same nationality living amongst us are and yet they are tainted as monsters all the same by a people that cannot differentiate. It's a shame that there was a complete non-reaction from the kids watching him transform because that strikes me as not only a major aberration (that sort of thing happens all the time in London, does it?) but also the episode ducking the chance to make a major comment on the paranoia of the British and how they would become violent and suspicious amidst racism. It ducks the approach to hold up a mirror to humanity and show the ugliest side to our nature, which is a crying shame. Although his committing suicide rather than face the wrath of a people that cannot accept his nature is very powerful.

* The Osgood box is essentially the opposite of the Osterhagen Key from Journey's End. That was a genuinely destructive piece of hardware encapsulating the most extreme reaction to a world gone to hell. The Osgood box inverts that, an concept to keep the peace posing as a piece of hardware holding the solution to a world gone to hell. I'm not sure either are entirely convincing in real life terms but they both provoke some strong drama and work within the terms of their narratives.

* 20 million Zygons exposed, it's a fascinating new take on the standard invasion notion. So strong I almost wish they had had the guts to go through with revealing them and forcing the show to make a comment on the reaction of a world that learns that aliens are among us... It would probably be something like the reaction to the ghosts as Cybermen in the series two penultimate episode, abject terror. But how much more interesting would it be to see 20 million peaceful Zygons exposed? How far would our humanity extend to these non-violent immigrants? It's a fascinating prospect...

*...and yet the ending of this episode is so powerful in it's implications of nothing happening to change the status quo it justifies its decision not to expose them.

* For the first time since her conception Kate Stewart is written as a person rather than a series of one liners. She's allowed to display genuine sentiment and not just sass. Is that because somebody else is writing for her aside from just Moffat? Very possibly.

* Ingrid Oliver gives another gorgeous turn as Osgood in what is turning out to be one of my favourite original recurring characters from the Moffat era, weighing in against an awful lot that I have grown tired of. My only problem with Osgood comes at the end of the episode where Moffat cannot resist by reset the situation so we have two versions of the same character back in action - he cannot bear to lose a single character, can he? I know it is technically a different person but essentially the status quo has been restored in every way and that's a little too tidy for my tastes given how catastrophic this situation was posed. And I rather liked the psychological angle of Osgood having to cope without her doppelganger. 

The Bad:

* I mentioned in the last episode that it could be potentially awkward to feature a possible plane crash in any piece of fiction because you never know what might be coming up next in the news. Allow me to quantify that statement. In the wake of a devastating plane crash amid political scandal to see two characters walk away from the devastating wreckage of a fictional planet crash in such a cartoonish fashion is a bit awkward. It's bad timing and the fact that this episode aired amidst the mysterious circumstances of a genuine disaster is unfortunate and impossible to predict. It does make me wince a little though, and probably always will. In essence it reminds me of the opening episode of The Lone Gunmen which featured a plan to bring down the Twin Towers with a plane just six months before that shocking event happened for real. In an episode that is purporting to look at conflict through mature eyes, this is pretty crass and unconvincing stuff.

* The Clara/Bonnie material was potentially probing but far too surface level and gutless to truly get under the skin of either character. For a story that wants to present Doctor Who as more than just science fiction, The Zygon Inversion avoids the chance to tackle Clara in a psychologically disturbing way. And I think that is because she essentially a surface level character and always will be. You can't scratch too deep beneath the surface because ultimately she is hollow. Quips and concepts, rather than personality and character. That's what Clara is And that's what this material is. So whilst I appreciate the claustrophobia of the visuals (Clara trapped in her own flat is a compressing experience), these scenes quickly run out of innovation and steam.

* Did Rebecca Front's character die? Did I miss something? Dropping her from the action all of a sudden is very strange. What a thankless role for such a great actress.

The Shallow Bit: Coleman as Bonnie; what is it about an evil companion that is so damn hot?

Result: Each Doctor has a scene where they give a performance so raw and mesmerising that it is possible that every other scene during their tenure can be judged by. For Eccleston it was his agonised turn as the war-torn Doctor in Dalek, Tennant arguably delivered his most astonishing work when pushed out of his comfort zone (Human Nature, Midnight and The Waters of Mars), Matt Smith dazzled in the quietly intimate Vincent and the Doctor and John Hurt sparkled throughout Day of the Doctor (I'm frightened at the thought of how good he would have been long term). Now Peter Capaldi has been handed what is essentially a star vehicle in The Zygon Inversion, a ten-minute monologue on the pointlessness of conflict and the need to talk that stripped away all the irritating quirks that have been bolstered on to his character this year and allowed the actor to captivate the audience in the way that only he knows how. It's quite simply astonishing. So astonishing that it rises head and shoulders above much of what the rest of the episode is doing and provides a hugely memorable climax to the piece. Capaldi is so convincing that he hands the story an ending where absolutely nothing happens...and it is all the more powerful for it. Climaxing a potentially catastrophic conflict on an intimate moment of drama is a risky business (Simon was expecting something much more showy and despite the performances couldn't help but feel let down) but for me it pays off in spades here. Which is good because this turns out to be one of the least effective invasions (remember the title of the previous episode) the show has ever presented but I guess they are admitting that ultimately this is nothing of the sort with the title. It's more The Zygon Co-habitation, although I guess that doesn't quite have the same gumption. The Zygons, whilst visually captivating, turn out to be some of the worst tacticians the world has ever seen. There are so many ways they could have caused disruption and devastation on a massive scale aside from searching for the Osgood box that I have to question whether Bonnie was genuinely invested in the idea in the first place. Davies used to stage invasions on an epic scale with flair and colour, this is a much quieter, less showy affair which for much of this episodes running time made me wonder what all the fuss was about. It's the blink and you'll miss it invasion featuring monsters that change their mind at the last minute and achieve very little. And yet within this whispered conflict there are some lovely, subtle touches and visuals and the comment that utopia never lasts forever and somebody will always come along and destroy the vision that you have fought so hard for is so achingly profound I was astonished that I had never had the point elucidated on television before with quite such clarity. What is war really for when nothing last forever? When there will always be another despot unhappy with the status quo. Why not sit down and talk instead of fighting when fighting is ultimately fruitless? A very worthy message, beautifully put across. Invasion/Inversion might just be my favourite of the year so far because despite the fact that the story as a whole is a series of missed opportunities it got me thinking and discussing the show in a brand new way. And that really excites me. What it didn't do got me thinking about a direction the show could take with a braver production team. It sounds like a backhanded compliments to say where this episode failed thrills me and maybe it is. But the fact that it took a risk (even if it didn't push it far enough) planted a real seed of interest. A fresh and original approach that doesn't quite work is still a fresh and original approach. It could be tighter with stronger characterisation and stronger in it's sentiment but it is a stepping stone to a new type of new Doctor Who - one with a political agenda and driven by anger. This is an episode that provokes discussion and gives people, fans and non fans a like, a something inflammatory to talk about and that can only be a good thing, whether you agree with its politics and the conclusions it draws or not. That and the extraordinary ten minute performance-piece from Capaldi is more than enough to weigh against the episodes flaws and deliver a confident: 8/10