Sherlock Photo: BBC

The good news is we’re definitely getting more Sherlock. The bad news is it probably won’t be for some time. There was a two-year gap between seasons two and three, and Benedict Cumberbatch and Martin Freeman are only getting busier. For the near future, fans will have to just keep rewatching this last batch — especially Sherlock’s excellent best man speech — but to give them closure, I sat down with the series’ executive producer Steven Moffat to discuss burning questions from the season finale, “The Last Vow,” in this order: Moriarty, Magnussen, mum, the mind palace, and Molly. (Spoilers for those who haven’t watched the finale yet, obviously.)

He’s aliiiiiive. I think? Is Moriarty the long game villain for the show?

I can’t really say what we’re doing with that, but there is no last-minute whim in this. We’ve had what we’re going to do with Moriarty in place from before the second season. Exactly what we’re going to do. I remember talking it through with Andrew Scott, who plays Moriarty. Wait and see what’s going to happen.

Are you running with Moriarty because of Andrew’s performance, which is great, or had you planned the character as an ongoing presence prior to casting?

Well, obviously Sherlock Holmes must have a Moriarty. The thing that happened that was different because of Andrew was that, originally, in “The Great Game,” the only scene that you saw Moriarty in was when he plays who we used to call Gay Jim. Gay Jim from IT. He comes in and Sherlock deduces that he’s gay. It was quite good. At the very end, Sherlock would have realized that he was Moriarty and that he’s just missed him. The great game has begun! But we weren’t going to see Moriarty again.

The problem was we had to then cast Moriarty on the basis of Gay Jim, but know he was going to be our Moriarty. So I wrote the most daft scene, the most ridiculous scene anyone’s ever written, as a confrontation between Sherlock and Moriarty just for the audition. It’s full of the maddest dialogue. “I would burn the heart out of you!” and all this crap, just to see if anyone could say any of this shit. And then Andrew came in and he did it and he was amazing. I said to [executive producer] Mark Gatiss, “Well, not only are we gonna cast him, but we’ve got to do a version of this scene now.” So we just changed the whole end of the episode to include a confrontation in the swimming pool — which has never made much sense, let’s be honest. Why? Why did he do it? Why now? What’s he doing? But you don’t really complain because Andrew Scott comes on for the first time and he’s incredible. If you really want to entertain yourself, watch that last scene back to back with the first scene in “A Scandal in Belgravia.” In just a few minutes, you have the most ridiculous set of events you’ve ever seen in your life. If you just show those two things together to someone and say, “This is what Sherlock is like,” they’d be like, “What? What the fuck is this series? What are you all on?”

I liked, but was surprised that Sherlock kills Magnussen. Is it going to affect him next season?

[Laughs.] People are worried so much about that! Have we forgotten that John shot someone in the back in episode one? And then had a giggle about it? Do you know what? I would have shot Magnussen.

It was the right thing to do, but …

I think people who behave like that should get shot. I don’t have a problem with it. If someone treated my family like that I would kill them and I’d spend absolutely no time worrying about it beyond thinking, It was really messy, wasn’t it? It’s a bit icky when he was bleeding all over there. But fuck it, if you behave that way, what do you think is gonna happen to you? I don’t think that will change Sherlock. He certainly won’t be haunted by guilt. He’s way in control of his emotions enough to say, “It’s time to switch that man off.” And again, he’s friends with John, who was laughing after he shot a guy minutes after he did it. C’mon! These are dangerous boys.

The really interesting thing is if Sherlock Holmes hadn’t blundered like an incompetent into the room where Mary was going to shoot Magnussen. She’d have just shot him, then she’d have gone back to being Mrs. Watson and they all would have been living happily ever after. Sherlock would be saying, “It’s really great someone shot him!” and he and Dr. Watson would carry on solving crimes unaware the killer was moving around them all the time, just killing anyone who was trying to attack them. Their secret protector.

Sherlock’s parents turned up this season (played by Cumberbatch’s real folks), and they’re pretty normal! How did they wind up producing kids like Sherlock and Mycroft?

Any time anyone has ever speculated on the parents of Sherlock Holmes they say he must have had a cold and loveless childhood. But that’s baloney! Sherlock and Mycroft are not the kind of kids who would have resulted from cold and loveless parents. Timid, frightened children are the product of loveless homes. Adults who are completely confident and don’t mind being different from everybody else, that’s the product of a very, very loving home life. That’s the product of someone always being told, “Doesn’t matter. You don’t have to be like anybody else. You can be who you are. Just be who you are.” This is what Sherlock’s been told, possibly too often given how he turned out.

So first we said he had loving parents, and at a certain point we thought, Do we dare bring his parents on? Then we dismissed the idea. But then we thought we weren’t being true to the updating unless we see them, because while I understand a Victorian man in his thirties might not have much of a relationship with his parents, I find it very hard to believe a man in the modern day wouldn’t know his mom and dad. He just would. They’d be part of his life. So they’re gonna turn up on Baker Street. We do reveal of course that one of them, mum, is actually super clever. The brains have to come from somewhere. But yeah, they are the product of a loving home and parents who just think they’re great anyway.

How did you come up with the look for Sherlock’s mind palace?

First, mind palaces do exist. People have them. I can’t because I’m not clever enough, but clever people can have them. You construct it out of spaces you’ve actually been in. You start in a house you live in and you put things in it and then you maybe join it to a theater you know well or something. So you’ve got a map in your head of places with which you’re familiar. The look of his mind palace would be conditioned by where Sherlock had been. There had to be places in contemporary London he knew well. And of course as he falls apart, as he gets shot, it becomes a bit more surreal. He’s a man in a mad dream trying to stay alive.

Molly started as a girl with a crush on Sherlock and has since become one of the most important people in his life. She’s up first in his mind palace, and saves his life after Mary shoots him. Can you talk about her evolution?

She’s developed hugely. She wasn’t even meant to come back after her first appearance, but she worked so well. Louise Brealey was so good. The girl with the unrequited crush became the first person to make Sherlock apologize in “A Scandal in Belgravia,” and then you see it really shift around. Whereas all of Sherlock’s emotion on the rooftop when he’s talking to John in “The Reichenbach Fall” is completely faked — he’s just trying to give his friend a bad time so he’ll be in an emotional state to believe what’s about to happen — the emotion when Sherlock turns up to Molly in that episode and says “I need you,” I mean, it’s amazing everyone didn’t just get it right there. For God’s sake, what do you think he’s thinking about? He’s gone to a woman who works in a morgue — what do you think happens next? So she’s become one of a very small select band of people he absolutely trusts. And he adores Molly, of course he does. He loves her. I don’t think she has the same sort of crush on him anymore. She’s fascinated by him, but she knows that’s not who she actually wants to end up with. She properly cares about him — and gets angry at him, and tells him off. It’s revealing that she’s in his mind palace. She’s one of the people he keeps himself up to the mark with.