Let me put you out of your suspense. Five stars. This is it. This everything I’ve been looking for all season long.

Is it perfect? No, not quite. But I don’t require perfection for five stars, if enough elements are strong enough. I will defend Kill the Moon to the death. Does that mean I don’t think that the science is total and utter garbage that doesn’t even make intuitive sense? Of course not. But the moral dilemma and the presentation of the Doctor’s relationship with Clara is so outstanding, I’ll happily give the gibberish biology a total pass.

So, let me get a few gripes out of the way early on, then we can all luxuriate in praise. This episode balances the needs of the four main characters better than anything since episode one. Yas is the most side-lined, but Ed Hime doesn’t overstuff the supporting cast and manages to give Graham a real stake in the action – and, for basically the first time – Ryan too. But Ryan’s early interactions with Hanne are so clumsy and frankly shitty, I question why he’s allowed on the TARDIS at all. By the end of the episode, it’s easier to see that this gives him an arc, but the barrier for entry to the most incredible ship in the universe has never seemed lower.

Also, the Doctor’s lying to Hanne about the “map” she scrawls on the wall is unconscionably awful. It pays off at the end, and it’s great that Hanne wasn’t fooled, but it’s still a fairly hateful thing to do, and unlike previous displays of lack of empathy from her male-presenting predecessors, she isn’t criticised or punished for it. It just stands. Also, I didn’t like her promising the sonic to Ribbons, when clearly she had no intention of keeping this promise.

And lastly, we can now add “wee” to the “chicken poo” from Not-Really-Demons in the Punjab to our list of potty training words that have somehow made their way into a Nebula-winning science fiction programme.

I think that’s it.

Yup, those are all my complains.

I know, I know. But read on…

Let’s start with what’s good. The set-up is briskly efficient. Hanne is an engaging character, well-played by Ellie Wallwork. The mystery is clearly established, and the mirror/portal is a splendid and sudden left-turn. The anti-zone acts as a plot-delaying device more than anything else. That’s not a criticism, merely an observation, because while you can imagine a version of this story which deletes the buffer zone between dimensions, and just has the characters stepping from one version of the house to the other, a lot of what happens in there is the episode’s most visual striking, funniest and contains the most genuine peril – something which has been in short supply this year. And who could complain about extra Kevin Eldon.

Everyone’s actions throughout are clearly motivated and spring from character. Hanne knocks Ryan out and heads for the portal, against the Doctor’s instructions, because she doesn’t trust him, not because the plot requires her to. And the arrival of Team TARDIS in the mirror universe is genuinely surprising, unsettling and unpredictable.

And then WHAM! The episode drops the other shoe like an anvil. Finally, Graham’s grief over Grace – in early episodes either ignored or inappropriately painful given the hijinks elsewhere – means something. It connects to the theme of the episode, it increases the jeopardy for the characters and we get a proper stitching together of emotion, adventure and high concept in a way which we haven’t seen frankly since World Enough and Time. I’m amazed that Chibnall, who presumably had some kind of scene like this in mind when he wrote The Woman Who Fell to Earth, let another writer deliver the punchline. Or maybe he didn’t have this in mind at all, and Ed Hime just saw the opportunity. Whatever, I don’t care. This episode is too good. And Bradley Walsh is sublime.

The Doctor – and it really is the Doctor all the way through this episode – desperately tries to get the humans to reject those they’ve loved, while the Solitract universe starts to tear itself to pieces. Jamie Childs does a wonderful job here, creating the apocalyptic atmosphere the script demands, aided by some of Segun Akinola’s best music.

And then it all comes down to the Timelord and the talking frog.

You don’t like the talking frog? Fine. Okay. I get it. It’s a bold choice, for sure. And if you don’t like it, I understand. It’s a pretty pisspoor special effect too, but c’mon. We’re Doctor Who fans. We can take it.

For me, it hardly matters what form the Solitract takes. For it to take a form associated with Grace, but which isn’t Grace, makes perfect sense. And the image is one which only Doctor Who could provide.

We’ve one more episode to go. I frankly doubt this series can do any better than this.

Ed Hime for showrunner.