By the end of “Deep Breath,” Peter Capaldi’s debut episode as the Doctor, you’re not going to know how to feel about the Doctor anymore. But that’s alright. Sort of. Because neither does he.

Capaldi’s casting as the Doctor made waves when it was announced in August 2013. The actor is a known quantity, utterly unafraid of depicting the rough edges of humanity, and a simultaneously inspired and insane choice for such a beloved character as the Doctor. As viewers we have become accustomed to the frivolity of Matt Smith and David Tennant, and the emergence of Capaldi in the role hinted at a dramatic shift away from Doctor Who’s lighter tone. Perhaps too much of a dramatic shift?

A housekeeping note: This is a non-spoiler review of the episode. Although it has debuted on the Doctor Who World Tour this past week the episode won’t screen at large until August 23. There will be few, if any, plot or twist details below.

Really, the big question that “Deep Breath” has to tackle, like any post-regeneration debut, is determining who this new Doctor is and whether that Doctor is interesting or appealing enough to follow.

Steven Moffat does post-regeneration stories well. “The Eleventh Hour” was a charming madcap introduction to Matt Smith that paid homage to Tennant’s reign while shifting the tone, and “Deep Breath” accomplishes a similar shift from the charm of Matt Smith to the, well, alarm of Peter Capaldi. “Deep Breath” does more than portray a shift in Doctors, however. The debut episode presides over a shift in tone and speed for the entire show. Doctor Who is changing, has changed, and by the end of “Deep Breath” is not a show you’ll recognize as Doctor Who.

This is deliberate. The episode puts the entirety of its effort into making this transition work and takes its time exploring the various ways that Capaldi’s Doctor will and will not appeal to us, his companions, and his enemies. Comparisons to the Doctor’s previous lives begin to show up everywhere as Capaldi’s Doctor begins to pull himself together, and the more they do the greater the contrast becomes between what came before and what we’ve gotten into now.

This culminates in a heart-aching moment near the end of the episode, where it becomes clear just how far away Matt Smith’s Doctor is now. Capaldi’s Doctor is, perhaps more than any other regeneration before him, a new Doctor. Throughout the entire episode you keep waiting for Capaldi to remember who he was, or to stop resisting the urge to be charming and Matt Smith-esque. And that never happens. The Doctor is a new man, and you have to accept who he is now.

Perhaps for the first time in her tenure as companion, Clara is our representative through this struggle. Jenna Coleman gets more to play with in “Deep Breath” than she has in all the rest of her episodes combined, and it’s honestly a relief to have someone to experience Capaldi’s Doctor with. You’re not going crazy, this is all really weird and kind of upsetting, and Clara’s there to confront it with you.

And there’s a lot to confront, really. This regeneration has severely rattled the Doctor and he is more alien and distant than ever before. So much so that even by the end of the episode you are not convinced that he knows who he is, what he’s doing, or even what he wants to do. The assurance that has defined the Doctor for years now is gone. He can still make the hard decisions, he even sort of dares you to let him make the hard decisions, but he doesn’t let on why he’s making them, not even to himself.

Capaldi plays this marvelously. He’s present and vibrant in every single one of his scenes but somehow still distant, as if he’s been shattered into a thousand pieces and he has to check every single dark corner just in case there’s a piece of him there… He’s not someone you want to cross. He’s not really someone you want to pay attention to you, even. (Unless you’re a dinosaur. He’s got an enormous soft spot for dinosaurs.) Capaldi’s Doctor is interesting, and not because he loves scribbling weird things in chalk, or hates doors and his eyebrows, but because he’s still as charismatic as ever. And that’s the one thing that remains the same about the Doctor. That’s what’s going to keep you hooked into watching this Doctor slip and stomp across time and space. He’s completely different, dangerous, and fascinating.

And he’s not done. By the end of the episode it becomes clear that this season of Doctor Who is going to be about both Clara and the Doctor finding their way back to…the Doctor. There are bound to be some infuriating and dramatic stumbles towards that along the way, and in that sense we may be in for the most interesting season of the show yet. This is a Doctor that you can put into a familiar situation and not know what the outcome will be. And that’s very exciting.

It should be noted that the difference in Capaldi’s Doctor is reflected in the show itself. “Deep Breath” is an apt title for his debut episode, as it takes its time to let scenes play out, to let characters interact outside of panicked plot situations. The show is slower as a result, but gains far more depth than it has ever demonstrated. An excellent balance is struck and I found myself wishing we had gotten this pace from Matt Smith’s episodes, really. His Doctor always zipped through a room, Capaldi’s stays put and forces all eyes onto him. The show is more substantial now.

While Doctor Who has largely nailed the shift in tone between Smith and Capaldi, and made Clara a real character, there are still some false moments. Everything you dislike about Moffat’s writing is in “Deep Breath,” unfortunately. Repetition of ideas, repetition of phrases to instill horror, stupid jokes about gender, needless insults about gender, etc. But we can get into those once the episode is officially here.

So. Peter Capaldi is the Doctor now and you should be worried. And fascinated. And hooked into the show in a way you possibly haven’t been in a long time. I’m really glad this season is going to air unbroken. It’s going to be an interesting ride.

Chris Lough is the programming manager at Tor.com and writes about things occasionally and occasionally a lot.