Clara is in what appears to be her flat, but she soon realises that this is a dream after looking at a newspaper with a seahorse on the front cover and finding the phrases “truth or consequences” in there. She is trapped inside a Zygon pod.
Bonnie, the Zygon who is assuming Clara’s form, finds another Zygon who has been living as a human, and forces him to transform back to his Zygon form.
It transpires though that Clara has some limited control over Bonnie. She makes sure that Bonnie’s aim with the rocket launcher doesn’t quite hit the plane on first shot,
though Bonnie’s second shot does hit it. The delay gives the Doctor and Osgood time to parachute out before the second attempt. Clara also manages to send a text to the Doctor. The Doctor calls Bonnie, and Clara is able to make her wink at certain points to give away Bonnie’s location.
Bonnie goes to Clara’s pod, and threatens to erase her mind. Clara counters by temporarily
transforming Bonnie back into her Zygon form. The mental link goes both ways. Bonnie says their heartbeats are also linked, so she can kill Clara, and she can tell if Clara is lying.
During the conversation, it is revealed the Osgood Box is under the Tower Of London, and the only ones who have access to it are the Doctor, the Osgoods and Clara.
The Doctor and Osgood arrive at the shop Bonnie was at, finding the Zygon she
transformed. He is distraught and cannot control his transformation. He just wanted to live on Earth and never wanted to fight anyone. He kills himself. More Zygons arrive, including one who is apparently assuming the form of Kate Stewart, and they take the Doctor and Osgood with them to the Black Archives. It turns out that it is the real Kate Stewart however, and she kills the other Zygons.
In the Black Archives, Bonnie has bought along Clara’s pod so she can get access. There are two Osgood boxes, one blue and one red. One box will unmask every Zygon on Earth. The other box will release a gas that will kill every Zygon on Earth. Not only that, but
each box has two buttons, labelled “truth” and “consequences”.
The Doctor, Osgood and Kate Stewart arrive. The Doctor reveals that the blue box unmasks Zygons and the red box kills them, so Bonnie is at the blue box and Kate moves to the red box. But it’s not quite that simple with the fact both have two buttons. One button on the red box will unleash bombs over London, while the button on the blue box will trap the Zygons in their human forms for the rest of their lives.
The Doctor tries to talk both of them out of pressing any button. Bonnie wants a war, thinking the Zygons will win. But even if they do, what then, asks the Doctor. That won’t be the end, because it never is. There will be more wars, and at the end they’ll still have
to negotiate with the opposing side. The Doctor sees war as ultimately futile, and
having been in the Time War, and wants to avoid another. Bonnie realises something. Both boxes are in fact empty. All they are is a deterrant to keep the peace treaty. Apparently this has happened 15 times, with the Doctor wiping their memories. He decides to wipe the memories of Kate and some of the Zygons, but not Bonnie’s. She calls off the Zygon splinter group.
Osgood will still not reveal if she is a human or a Zygon. Furthermore, there are now two Osgoods again, as Bonnie has decided to not use Clara’s form anymore and use Osgood’s instead. They choose to stay with the Osgood boxes to continue to protect the peace treaty.
We learn that Osgood’s first name is Petronella. I suppose you can’t blame her for preferring to go by her surname.
Osgood would make a good companion, and she has that role here taking over from Clara. She is even offered a chance to become one by the Doctor, but it seems she’s going to remain a semi-regular character instead. Or “characters” I suppose, as there are two Osgoods again.
Jenna Coleman was good as Bonnie, particularly in the scenes where she was talking with Clara, managing to show the difference between them.
The Doctor once invented an invisible watch… he is aware of the massive design flaw there.
‘The Zygon Inversion’ was another episode about choices, consequences and the struggle to keep peace. The conclusion it draws is that war, ultimately, does nobody any good and just generates more suffering, so even is peace might even seem to be the harder choice, it’s the better one. The episode works as a drama, being very compelling and even the fact that it seems on a smaller scale to episode one, focusing on just the core characters, works as it allows the audience to see it from a closer perspective.