‘I thought I was just being kind, but I was saving the world.’ It’s an interesting choice to pay off this three-parter with a reimagining of Last of the Time Lords, complete with the Doctor’s companion wandering a subjugated Earth covered in enormous statues of its lords and masters, to rescue him from the prison ship where he’s being held before they hack into a psychic signal, unwind time and become the only people who can remember the half-year that never was.

Fortunately, I like Last of the Time Lords, so I’m more inclined than not to like this. I particularly enjoyed Capaldi at his most ebullient, laughing madly on the prow of a ship as he sails back to free Great Britain from the Monks. Mackie is also great both in conveying a lot about the state of the nation in her desperate appeals to an apparently-turncoat Doctor, and in her almost proud martyrdom as she heeds Missy’s advice on how to break the Monks’ spell.

This is important, because Toby Whithouse’s script spends less time than RTD’s in actually showing us the world the Monks have created. We get the gist from the scenes of a Nineteen Eighty-Four Ministry of Truth imprisoning dissidents, and the generally beaten-down appearance of most of the characters, but it mostly relies on Mackie’s performance. Even then, it’s a stretch to believe Bill is ready to shoot the Doctor dead without making more effort to turn him back. I didn’t buy it, or the slightly contrived way to force the Doctor to open the vault to consult Missy. This whole “arc”, since Oxygen, has felt a little bit mechanical at moments (the bargain to restore the Doctor’s sight; the crisis that unleashes Missy) – logical storytelling is important, but I don’t necessarily want to see the infrastructure.

So, it ends – as it must – with the Monks both banished and forgotten, Bill and the Doctor restored to the status quo ante Oxygen, and Missy finally showing remorse for all the murders (amusingly, she does this like Sylvia Noble in Turn Left, remembering all the names of the dead). The Doctor’s kindness to Bill, the photos of her mother, prove crucial to the resolution, and the mid-series climax all ends well.

As an arc, I’m don’t think it worked, it creates a huge rock in the middle of the Doctor and Bill’s episodic adventures, after the first half of the series focused so hard on telling accessible adventures for all the family. But it does function as a turning point. Missy is back, she’s a changed woman, and Bill’s saved the world in a way most companions don’t get to do until a series finale. Where do they go from here?

Next Time: The Empress of Mars