The previous episode of Doctor Who had set up an almost impossibly difficult situation for the Doctor to resolve. It was something that managed to touch on aspects of both a refugee crises, and terrorism - all of which was wrapped up in the story of an alien invasion. Despite the issues I had with the episode, as a whole, it was still a tense and genuinely compelling set-up - and, I had been genuinely uncertain about how it could possibly be resolved.
The cliff-hanger on which the previous episode ended, though, was significantly less interesting. We had the Doctor and the sole surviving Osgood trapped on a plane about to be blown out of the sky. We had Clara's evil Zygon double as the one with her finger on the trigger of a rocket launcher. And, we had, seemingly, only moments left until the Doctor and his temporary companion died. It felt like a particularly contrived cliff-hanger, even by the usual standards of contrived cliff-hangers - it was really just a matter of whether the Doctor's inevitable escape came across as genuinely clever, or just kind of cheap. Well, in the episode's opening moments, we get an escape which, somehow, manages to be both.
But, thankfully, this will all be over before the opening credits - so, it's not a major distraction.
Believing herself to be free of the Doctor's meddling, Clara's evil Zygon double (or, Zygella, as the Doctor later comes to call her) is able to continue with her plan to force a war between her own species, and the humans - something which, almost immediately, pushes this episode into some thematically dark territory. The first step of her plan, it turns out, is to force one of her own kind out into the open - leading us to a small sub-plot involving an innocent Zygon who, it is made clear, is perfectly happy living out his life in human form. This Zygon (Nicholas Asbury) clearly represents everything that Zygella has come to despise about her own race - so, there is definitely a disturbing element to the way that he is forced to transform back into his natural form in public. I do have to admit, though, that the scene itself was a bit strange - having him transform in front of a group of typically slack-jawed teenagers, who went on to give absolutely no response, just left me a bit confused. Were the teenagers also Zygons taking part in a staged video that Zygella was recording? Or, were they just too stoned to react? It wasn't made clear - but, it was a very strangely shot scene, either way. This seemingly inconsequential sub-plot did, ultimately, lead to a resolution that is, perhaps, one of the darkest and most depression things to every happen on Doctor Who.
Of course, this is just a distraction, in the end. Zygella's true plan is to get her hands on the 'Osgood Box' - a secret weapon developed to be used in the event that the peace treaty between the two races were to break down. Despite not actually knowing what it does, Zygella clearly believes that it is exactly what she needs to force the war that she believes is necessary - a war that she believes will set her people free from what she sees as a form of imprisonment among the human race. Clara, meanwhile, continues with her efforts to subtly influence her Zygon double - reaching out from the strange lucid dream she is trapped in to try to find some way to contact the Doctor.
It is never really explained exactly how Clara is so easily able to do this, though - something which is especially frustrating when you consider the clear implication that she is the only one who could. Basing such an important point of plot development on the fact that Clara is amazing, and we all just need to accept that, probably wont do anything to win over those members of the audience who already dislike her - but, it is what it is. There's not much sense in dwelling too much on it.
All of this is, obviously, leading to the seemingly inevitable stand-off for possession of the Osgood Box, itself. But, of course, there is still the important question of why it is called the 'Osgood Box', in the first place. Well, it turns out that much like its namesake, the Osgoods themselves, there are actually two of them - one red and one blue. One intended for the Zygons, and the other meant for humans - with each, it turns out, containing two buttons. It is a situation deliberately set up by the Doctor, himself - something which, he claims, provides a perfect analogy for the act of war, as a while. It is, essentially, a weapon which gives each side the power to destroy the other, but at the potential risk of destroying themselves.
So, while it might feel a bit contrived to have all of the important parties reach the Osgood Box at the same time, the scene that results is the true high-light of the episode - and, maybe even of the entire season, so far. On one side, we have Zygella - who believes that her own race are the victims of an unfair treaty which forces them to deny their own true identities. On the other side, we have Kate Lethbridge-Stewart, representing the human race against an aggressive alien force. And, at the centre, there is the Doctor - desperately trying to keep the peace.
It's a great scene for everyone involved - though, it's a fantastic scene for Peter Capaldi, in particular. Through his performance, we are given an entirely convincing portrayal of the grief and desperation of an ancient alien being, frustrated by what he must see as essentially childish anger. Though, credit should also be given to both Jemma Redgrave and Jenna Coleman for their parts in making this final scene so great - each being perfectly capable of convincingly portraying the devastating stakes at play. Jenna Coleman's ability to convincingly portray two distinctly different characters within the span of a single episode also deserves credit - as does her ability to make Zygella into such a convincingly complex character over such a short period of time.
For, perhaps, the first time this season, the resolution to the central conflict of an episode of Doctor Who doesn't feel as though it comes to easily. Instead, it feels entirely earned. The episode presents a difficult situation, in which neither side is entirely right or wrong - and, rather than attempting to gloss over that fact, the episode ends with a scene that fully acknowledges the almost impossible situation it had created. I came into this episode convinced that there was likely to be no truly satisfying way that the show's latest two-part story-line could be brought to a satisfying close - and that, perhaps, Doctor Who was trying much too hard to be topical and relevant. But, the show managed to genuinely surprise me, here, with a fantastic final scene which might make this one of the show's most memorable recent episodes.