With “Heaven Sent” we have a unique occurrence in the history of Doctor Who — an episode featuring the Doctor and no other character. We’ve had other similarly unusual situations in the past: “Ark in Space” part 1 includes only the Doctor, Sarah Jane and Harry, with no guest characters. Same with “The Mind Robber” part 1 with the Doctor, Jamie and Zoe. The Season One 2-parter “The Edge of Destruction” features only the main cast for the entire story. The one-episode adventure “Mission to the Unknown” does the opposite trick, featuring only supporting characters with no involvement by the Doctor or his companions. But we’ve never had a story to feature the Doctor — or any single character — exclusively. That premise alone is an enticing one that immediately brings a million exciting possibilities to mind. But what we’re given here is a mostly quiet narrative on loss mixed with some new revelations about the Doctor, the reintroduction of some of the threads from earlier in the season, and a set up for the season finale. That’s quite a lot of material to deliver with only one actor on hand (that must have made for quite an interesting table read!)

But to be honest, this didn’t exactly feel like a one-hander; Clara still had a significant presence throughout the episode, with the Doctor talking to her throughout. Heck, we even saw her numerous times. She even addressed him directly (yes, I know, it all happened in the Doctor’s head, but the on screen effect is the same). In fact, having just died last week, she was actually in this episode more than she was in “The Woman Who Lived”. [It’s interesting that in that earlier mid-season episode we got a taste of a companion-less Twelfth Doctor; it’s like the audience was being prepped for Clara’s departure.] Here, though, we’re shown a Doctor dealing with the loss and the guilt of seeing his best friend killed and not being able to do anything to save her. There is a moment where he asks his “mind Clara” what she would do in the graveyard with the shovel, and she responds “same as you.” The Doctor mutters, “Yes, yes, of course you would. Which, let’s be honest, is what killed you.” The Doctor lamented in “Face the Raven” that he’d let Clara get too reckless; here he’s dealing with the fallout from that and will carry the guilt of it for a while.

I said in last week’s review that I’d save my Peter Capaldi praise for this week so as not to detract from the focus on Clara. Plus even I was getting tired of me saying how brilliant Capaldi is every week. But the truth is … Capaldi is brilliant. He has been nothing short of astonishing this year. Not that he was anything less last year, but any Doctor’s first season is one of settling in, of finding one’s footing in a role that is unlike any other. Last year showed us what amazing stuff was in store for us with Capaldi in the TARDIS; this year delivered on that in a big, big way. And we still have (at least!) Christmas and all of next year to look forward to as well. I just can’t imagine how much more amazing Capaldi is going to get. It’s kind of a cliche to say that Capaldi’s take on the Doctor echoes so many of his predecessors’, but it’s true: There was a great deal of Pertwee in this week’s episode, especially the Pertwee we saw in his final story, “Planet of the Spiders”, in which the Doctor is forced to face his deepest fears. In fact, we learn possibly more about the Doctor’s younger days on Gallifrey during Pertwee, by way of stories he’d tell Jo Grant, than we do during any other Doctor’s tenure, just as here we learn about the old dead woman on whom the Veil is modeled. And Pertwee certainly had his share of castles (in “The Time Warrior”, the two “Peladon” stories and, essentially, the city of Exxilon). Capaldi brings a weight to this role, a substantiality. You feel the burden of centuries, and of the loss of a single life.

We also learn here that the Doctor didn’t originally leave Gallifrey because he was bored; that has always been a lie. He left because he was scared. But we never learn what it was he was scared of. What was it that drew the Doctor away from his home, compelled him to go on the run from his own people? What could have been so bad that he stole a rickety old TARDIS and ran away from home forever? Is that something we’ll learn next week in the finale? Or is it another of those mysteries that will hang in the air for years to come, maybe to be revealed at the 75th anniversary (hopefully not that long!)?

Apparently this whole episode takes place within the Doctor’s Confession Dial, which is a pretty neat idea. But why didn’t I pick up on that earlier in the episode? When the Doctor talks about needing to confess to keep the Veil at bay, why did I not make any connection at all to the Dial, which has been seeded very lightly throughout the episode? I knew that the Doctor was in something like a time loop very early on. There were clues at the beginning of the episode, not the least of them being that his appearance in the transmat tube (for want of a better description) seemed to be more traumatic for him than simply having been transported. And then there’s the shovel with dirt on it. The clincher was the dry set of clothes — it made sense that he was the one who’d left them there. What I did not predict was the brilliant nature of the loop. The idea of his repeatedly dying and recreating himself in order to erode the Wall over billions of years is a rather ingenious one. The clue to that was the skulls, but that early in the episode I just couldn’t piece that part together, not until the end where he picks up the one skull with the leads plugged into the temples. What a brilliant twist! So having made at least some of those connections, I should have connected the Confession Dail dots too. Alas, Moffat is still smarter than me.

This episode rounds out what has been an extraordinary season and sets up what promises to be a big, epic finale. Just in the two trailers we see Time Lords, Cybermen, Daleks, Weeping Angels, big space ships, a pick up truck in what looks like the mid-West, that barn from “Day of the Doctor” and “Listen,” different TARDISes, a firing squad, a crisis regeneration, and all sorts of other things. This is going to be an episode on the scale of the season opener, and it’s going to be a doozy. I’ve said before that this has been the best season of the 2005+ era, with the most consistently strong run of episodes (with only two possible exceptions of episodes that were weaker but still quite good) we’ve seen in the past 10 years.

And one final note: A lovely moment at the end of the episode when the Doctor says to the little boy “If they ask you who I am, tell them I came the long way ’round,” echoing what the Eleventh Doctor said at the end of “Day of the Doctor”:  “At last know where I’m going, where I’ve always been going: home — the long way ’round.” That puts a smile in my little Whovian heart(s).

If you enjoyed this review and would like to read more, order a copy of my book Doctor Who’s Greatest Hits: An Unauthorized Guide to the Best Stories From Time and Space!