As excuses to put Peter Capaldi in a top hat go, the latest episode of Doctor Who is a good one.

But as Doctor Who episodes go, it’s pretty fantastic.

“Thin Ice” comes from the hand of Sarah Dollard, whose “Face the Raven” was a rather subdued prelude to what might be the finest performance of Peter Capaldi’s career, and that’s going some. Here, she lands Twelve and Bill on the frozen surface of the Thames River in 1814. As it turns out, this was a real thing – said river used to freeze over regularly, and they’d hold “Frost Fairs” to celebrate.

Since the TARDIS brought them there without their asking, our heroes quickly gather that Something Is Not Right. So they make their way across and under the river, and just as quickly discover a monster lurking underneath… and an even greater monster, a human one, exploiting it from above the surface.

This plot gives Dollard an opportunity to make some pointed statements about society then and now, and (unlike the disappointing “Smile”), she runs with it. Through the adventure of “Thin Ice,” Doctor Who offers commentary (some subtle, some much less so) about racism, about the whitewashing of history, about the way we treat the poor. We get Bill, as ever, questioning everything she sees, and sharing her heart with Twelve and with us (oh, Pearl Mackie is just SO GOOD). We get a patented Twelfth Doctor monologue about the value of human life, and needless to say, Peter Capaldi makes the most of it.

And in a bit of fist-pumping cathartic schadenfreude, we get to see Twelve so angry that he actually punches a guy in the face.

Few things make me quite so happy as when I get to say I unequivocally, unabashedly loved an episode of Doctor Who. And I unequivocally, unabashedly loved “Thin Ice.” Appropriately for an episode about a “lochless monster” lurking beneath the surface, it succeeds on so many levels. And the last scenes offer an interesting, ill-boding tease at just what – or who – is in that vault Twelve swore an oath to protect.

Episodes like this one are just making the inevitable goodbye to Twelve that much harder.

As before, thanks for following along. Until the next episode…