‘I don’t want to live if I can’t be me any more.’ Superficially, this has elements of Death in Heaven, with Bill’s retention of her personality and determination echoing Danny’s. But I think it’s more meaningfully like Hell Bent, exploring the idea of learning to let go, and accept that all things must pass. Surprisingly, the Master seems more comfortable with this than the Doctor: he’s not exactly rushing to become Missy, but he’s at least intrigued by the idea (though, as he tries on Mascara and fetishises her body, probably for the wrong reasons); while Missy literally laughs in the face of “death” (come on, she’s had her whole regeneration to come up with a way to survive that laser screwdriver blast).

Capaldi is astonishing. Throughout this series, he’s been the Doctor I wanted from the start. He gets some wonderful moments: explaining his strategy to a child with her toys; having to face the woman who was ‘dismembered’ after waiting a decade for him to get round to rescuing her; admitting he was wrong when he said he could put things right; reduced to pleading with the Master and Missy to stand with him, at the last, and just be kind. It’s clear he’s holding off regeneration throughout (thanks to that handsy Cyberman – never trust a hug), with a melancholy, hopeless defiance.

He’s surrounded by great performances. Matt Lucas gets his biggest role as Nardole, and plays it straighter than previously. His little facial reaction when Hazran accidentally shoots at CyberBill is perfect. Gomez is similarly brilliant in her reactions, selling Missy’s conflict and regret more through performance than dialogue. Only Mackie feels a little undersold by the episode – although only because she’s replaced by Nick Briggs’ voice and a Cyberman for many scenes. When she gets to play against Capaldi, she’s tremendous, and her ending, though clearly echoing Clara’s, feels like it’s bringing this series full circle.

Rachel Talalay’s direction favours these moments of intimacy: a shot of Missy’s eyes reacting to the Doctor; Bill’s Cyberman shadow falling on a wall. Even during the action sequences, we stay personal as the Doctor fights (and falls) alone on a battlefield, or the huddled inhabitants of this base under siege wait for the attack.

And she is working with a great script, full of sadness and passion, and a resounding defence of doing the right thing even when everyone criticises you and it would be easier to walk away (maybe Moffat channelling some Series 10 trauma here). There are some familiar tropes (deaths and miracle resurrections; quoting Terrance Dicks, and what is this obsession with barns?), but I think given it’s Moffat’s seventh series finale, and the second with the Master and the Cybermen, it feels remarkably fresh. Having avoided writing a traditional villain for so long, it’s also pleasing that Moffat finally gives us the Master at his absolute darkest: not because he’s got some universe-shattering plan, just because he’s cruel and cowardly and the genuine inverse of the Doctor. Missy killing him becomes the symbol of her redemption – too late, but at least she tried.

If this had been Capaldi’s final hour, I think it would be the strongest new series regeneration episode (its only real competition is The Parting of the Ways, which it somewhat resembles). We even get the preamble to the change, with callbacks to Planet of the Spiders, Robot, Logopolis, The End of Time and The Time of the Doctor. But the twist in the tail is intriguing. At the start of World Enough and Time we saw the Doctor battling regeneration in a snowscape – turns out, it’s the South Pole in 1986.

Next Time: Twice Upon a Time