The Doctor will see you now.

The adventures of the enduring and long-lived Time Lord continue when "Doctor Who" returns to the BBC on Sept. 19 with Peter Capaldi in his second extended stint as the Twelfth Doctor.

Ahead of the Series 9 premiere, the actor joined with series showrunner Steven Moffat and co-star Jenna Coleman to provide a Tardis-fueled peek into the future of the next twelve-episodes.

Editor's note: This interview was held prior to the announcement that Coleman is exiting the show at some point during Series 9.

On how the current Doctor is still in the process of discovering himself:

Steven Moffat: The Doctor always takes a moment to find exactly who he is. I don't know if we did that more with Peter or not, because Peter's Doctor is less on the charm offensive -- he's just on an offensive -- so maybe he doesn't cover that up to the same degree. But I think there's an interesting story to be told, and that you should always tell, of what it's like just to become somebody else and not really know yourself for a while. I mean, he might angst a bit and say, "Am I a good man?" "Answer: Yes," and, then, just blow up some Daleks as usual, really.

Peter Capaldi: It's interesting to explore how somebody develops rather than appearing fully formed. The idea that someone has to struggle to discover who they are is a fond story to tell. So I think that's what we are trying to do and continuing to try to do.

I had no idea how to play Doctor Who. Even today, I've got no idea how to play it. It's quite clear if you see the rushes. He's mysterious, and I think it's probably not a good idea to arrive with a solid, unbending idea of what you should do.

So much of what we do is collaborative and with wonderful scripts to work with and wonderful directors, and I like to try and develop things and see what happens. You can't, sort of, develop a role in isolation. You have to do it with other people. But luckily, because I was a big fan of the show and very familiar with it, I felt that I knew something of its tone, so I felt as if I didn't have to struggle to find that. But I quite enjoyed the fact and enjoy the fact that I don't really know how to play the part. I think it would be a bad idea to arrive with a fully formed notion of how you think you should be.

Jenna Coleman: It just felt like a whole new playing field, really. And as actors, I've been really lucky because Matt and Peter are both really open and inventive, spontaneous, fearless. So it kind of just felt like we were arriving at work and starting again on a new story together, and it kind of felt like a very open partnership from day one.

Moffat: Of course, it refreshes the show unimaginably when you change the lead character. It's not just casting a new actor in the same par; the part changes as well. And that's why "Doctor Who" is still alive. Because it becomes a new series. It's a star vehicle. It used to be the Matt Smith's star vehicle; now, it's the Peter Capaldi star vehicle. That's how it works as a show. It seems counterintuitive, in a way, because we keep changing the lead.

On where Clara starts the season:

Coleman: Post-Danny leaving the show the last series, her perspective on life, I think, has changed, and she's no longer divided between Earth life and a TARDIS life, so she can kind of go a TARDIS life full-frontal with nothing to lose. So there's definitely more of a fearlessness and a reckless abandon, I think, that Clara and The Doctor throw themselves into adventures headfirst.

On upcoming guest star Maisie Williams' as-yet-unrevealed role:

Moffat: Once you see what she's up to in the show, you'll appreciate what a clever idea of Brian Minchin's that was -- Brian Minchin, who is my co‑exec, who thought of Maisie for this part. And it's a significant role. We are not throwing her away. You know, we are not just getting the star value and doing nothing with it. It's a great part, and she's terrific in it. But I would say, it will develop in unexpected ways.

One thing I think is worth saying, because it keeps coming up as an issue: she is not playing a returning character. She is a brand-new character. She's not someone from the Doctor's past -- unless I'm lying.

On the return of Missy -- a.k.a. The Master -- as played by Michelle Gomez:

Capaldi: She's just so annoying! She's so wonderful and funny and clever and evil. Michelle plays it so beautifully. It's great. The role that she fulfills in the new season is rather different from what she did last time and what people would expect of The Master, so that's very surprising. Yes, she gives The Doctor a hard time.

Moffat: I had, really, no idea what we were going to do with the part. I'd known that we were going to do the Master and she would come back as a woman and we would see how that worked and if it would be good. Then I thought, "I've just done a gimmick. I haven't actually thought this through at all." I had a giddy moment in the office, and I was wondering who the hell could do that. Then I saw Michelle's name on a list for a different part in the show, and I thought, "Oh, my God. That's it. It could be Michelle. She would be absolutely barking. She would be mad. That would be wonderful."

And then I got an email that night from Michelle saying, "I'm really sorry I've had to turn down that part because I'm busy doing something else, but if you ever want me back as a razor‑cheekbone villainess, I would absolutely love to be in 'Doctor Who.'" So that was it. I just said, "All right. That's it." I didn't even reply to the email. I was that mean. I just went to the [BBC] office and said, "Look, do you know what? We are just going to cast Michelle." That's the only time I've been that bullish. I'm not usually that bullish about anything. I just said, "It's going to be Michelle. I know how to write it if it's Michelle."

So, yes, her extraordinary comic gifts and the way she can be sort of feral and frightening at the same time is delightful. It hugely informs me in the writers' room because I'm the only one who's written that character. So, yes, yes, it's a lot about Michelle. She's a genius. She's absolutely brilliant. And I like the fact that the Doctor and the Master are both Scottish now. I think that's excellent, piece by piece.

On the potential to take the Doctor into a feature film:

Moffat: Well, the thing about the film -- it's not actually up to me. That's up to the BBC. I, to say the least, don't own "Doctor Who." I make a television show for the BBC, and it will be up to them, but the circle to square, and maybe there is an answer, but I've never seen what it is, is, what are we going to do? Shut down for a year and make a movie? Does everyone really want that, one movie instead of a whole series? Or, you know, the idea that I've always been incredibly resistant to -- you'll be glad to know, Peter -- is the idea that you would have a different Doctor in the movie, because I think that would just be incredibly damaging to the franchise. You can't have two James Bonds at the same time. It's nonsense.

On whether a new Doctor is, even at this early stage, an inevitability:

Moffat: It's the only job in television where everybody asks you when you are leaving. That was ‑‑ and I'm not making this up ‑‑ the first question that David Tennant got at the preview of "The Christmas Invasion": Someone said, "How long are you planning to stay?" And he said, "I just got here. I've just arrived."

Peter is going to play the part for the rest of time. It's in his contract. It's perpetual. He is the Doctor forever.

Capaldi: I didn't look at the small print, so I didn't see that clause.