As the Capaldi era comes to an end, Steven Moffat has just three more chances to show us that his technical brilliance, his love for the programme and his vaulting ambition can work together to provide some really terrific storytelling, and not get in each other’s way as they are so wont to do.

The opening of World Enough and Time is unbelievably cheeky, with Missy proclaiming “I am Doctor Who and these are my expendables – Exposition and Comic Relief.” This almost feels last-day-of-school, but Moffat, guardian of the legacy, is always careful to provide a canon-friendly interpretation of the lines.

We find ourselves on board a miles-long spaceship, fighting the gravity well of a black hole, such that it is experiencing massive time dilation effects. This is a lovely science fiction concept, based in real physics, it’s just a shame that we saw another, slightly less rigorous version, last week. Suddenly, shockingly, Bill Potts gets a hole visibly blasted through her middle and then Cybermen bundle her off to the floors below. Although – if the Cybermen are evolving on the very bottom floors, where time is running the slowest, surely it should take them decades to even notice the presence of humans on the upper levels?

While the Doctor debates and argues, Bill makes friends with a shambling Fagin-like figure in the hospital on the ground floor. A lot of this is just vamping, and it’s slightly annoying that the time dilation isn’t ramped up just a little bit more. We know full well that the “hospital” is a cyber-conversion centre so the suspense is when and not if Bill will be fully converted. But the scenes of the Doctor working the problem feel a bit lifeless, which is a shame when the time dilation means that the Doctor and company could have headed straight for the lift and still been years getting down to where Bill is.

What’s brilliant about the stuff with Bill is how cleverly Moffat uses parts of the mythology which have gone unnoticed until now and provides justifications for them. Just as Clara’s calm words get turned into Dalek ranting in The Witch’s Familiar, and so we understand why Daleks sound the way they do, here the Cyber chest-units are retconned into elaborate surgical heart-replacements. And don’t the “Mondasian” Cybermen look fantastic?

About half way through the episode, I caught myself musing “I wonder when John Simm is going to show up,” and then I instantly realised that that’s who Fagin was. I honestly don’t think I would ever have got there without the advanced publicity. Shame on you, BBC.

Finally, at the episode’s end it all comes together. The Master is unveiled, Bill is converted, and the Doctor is at a loss. It’s a great part one, emphasising personal loss and avoiding the diminishing returns which set in when writers start trying to raise the stakes by having the threat become greater and greater.

The Doctor Falls takes an hour to wrap up – well sort of – what the previous episode began, but compare to season finales past, never seems hurried or over-stuffed. It’s nice to see the Doctor on the front foot so early on, springing into action and escaping to higher floors. The location footage on Sam Spiro’s farm somewhat fights the notion that we are on a gigantic spaceship, but there are sufficient reminders so this just about works and Rachel Talalay handles this visual conundrum very well indeed.

Shooting cyber-Bill as Pearl Mackie means we never forget the person inside the tin suit, and keeps hope alive that she will be returned, even if the rest of the script is dismantling that hope piece-by-piece. Her plight is hugely affecting and it’s clear that – for once – Moffat is thinking through the human side of the dilemma he’s created instead of just writing crossword puzzle clues for the viewers to solve.

The time dilation works for and against our heroes. On the one hand, it means that the Cybermen have time to evolve (another lovely piece of ret-conning – the Cybermen are not unique to Mondas or Telos, or Marinus(!), but are an inevitable by-product of technological advancement). But it also means that with each floor you go up, it takes them longer to follow. So Nardole figuring out how to selectively blow up parts of the ship buys them time, but more time than it might have done otherwise. (Although the justification that Nardole’s remote control device can’t be controlled remotely is astonishingly feeble.)

From here – the story follows three tracks. The fate of Bill. The fate of the children. The fate of the Master. They don’t really affect each other, which is not perhaps ideal. The Master can be removed from the story entirely without anything changing, but unlike the pointless cameo from Clare Higgins in Hell Bent, here they serve not just as something to cut away to, but underline the real point of the story, and indeed the point of the Doctor. I would have liked it underlined that the Master(s) leave the children to die not because they refuse to be kind, but because they are cowardly. But nevertheless, the Doctor’s desperate plea that they stand and fight with him, and their ironic mutual destruction add immeasurably to the episode’s bleak tone.

Bill of course, finds a saviour, in the form of The Pilot from Episode One. Again – serialised storytelling done right. This is not vaguely mentioning a past event in order to get a fanwanky cheer. This is setting up a figure with clearly defined abilities and proclivities and then dropping her back into the narrative when she’s needed.

The fate of the children and Nardole is rather less clear. The Doctor is totally backed into a corner here. Wounded, dying even. An army of cybermen below him which will only grow bigger. One opportunity to get innocents out of the line of fire. All he can do is send them a few floors up and hope that they have a few extra months or years – either to live and grow and be happy, or to think of another plan.

The Doctor himself, meanwhile, fighting off regeneration, stumbles out of the TARDIS and into the snowy landscape, presumably of the North Pole c. 1986 and meets – himself.

Well, we’ll judge this audacious move on the merits of the Christmas special, but let’s try and assess this two parter on its own merits.

Clearly, it’s by far the best finale Steven Moffat has written. The Big Bang barely makes any sense, and coming off the back of The Pandorica Opens with its absurd Monster Convention, it’s amazing that it works at all on any level. The Wedding of River Song is total gibberish, failing to wrap up the Lake Silencio storyline in any satisfactory way, and providing next to nothing in terms of narrative coherence. The Name of the Doctor doubles down on this kind of unintelligibility, although The Time of the Doctor makes it look like a masterpiece of structure. Time is surely the worst regeneration episode in the entire show’s history.

Under the firm leadership of Peter Capaldi, things improve. Death in Heaven isn’t a patch on Dark Water, but is still far better than any of the Smith finale episodes (maybe on a par with The Big Bang). Hell Bent, alas squanders the considerable capital built up by Heaven Sent, but this year’s pair work beautifully together to tell a complicated science-fiction story, that keeps its focus on the characters we love and care about, which doesn’t try and pack too much in to its running time, and which lets five amazing actors do wonderful work together. It’s telling how much more apocalyptic this feels than The Big Bang for example, not because the fate of the universe is threatened, but because the Doctor gives so much to eke out a draw against impossible odds.

A few little niggles in both episodes prevent me from offering up a full five stars but I’ll happily give four and a half to both.

Overall, this has been another very strong season, with only Smile and Knock Knock really letting the side down. Extremis makes not a whit of sense but is quite fun while it’s on and all the others have been good to great. Here’s my final ranking.

  1. World Enough and Time 4.5 Stars
  2. The Doctor Falls 4.5 Stars
  3. The Pyramid at the End of the World 4.5 Stars
  4. Oxygen 4.5 Stars
  5. Thin Ice 4 Stars
  6. The Lie of the Land 4 Stars
  7. The Eaters of Light 4 Stars
  8. Empress of Mars 4 Stars
  9. The Pilot 4 Stars
  10. Extremis 2.5 Stars
  11. Knock Knock 2 Stars
  12. Smile 1 Stars

And just for fun, let’s compare this to the rankings on Gallifrey Base to see just how in-tune or out-of-step I am with Doctor Who fans across the world.

  1. World Enough and Time 91%
  2. The Doctor Falls 86%
  3. Oxygen 82%
  4. Extremis 79%
  5. The Pilot 76%
  6. Thin Ice 74%
  7. Knock Knock 74%
  8. Empress of Mars 73%
  9. The Pyramid at the End of the World 73%
  10. The Eaters of Light 69%
  11. Smile 67%
  12. The Lie of the Land 64%

The fondness for Oxygen as well as the finale two-parter doesn’t surprise me, nor does how much people like Extremis. The excellent Pyramid coming so low down, beneath the awful Knock Knock is very surprising, and I would never have picked The Lie of the Land as the season’s worst. I wonder why people disliked it so much?

One more Capaldi episode to go. See you at Christmas…