‘Slow Horses’ Showrunner Breaks Down Season 3’s Ending – And Teases Season 4: “It Will Be Messy”

When Apple TV+‘s Slow Horses first premiered in April 2022, the thrilling espionage drama — based on Mick Herron’s popular book series — quickly established itself as a brilliantly crafted gem brimming with wit, captivating suspense, and standout performances from a stacked cast, including Gary Oldman, Jack Lowden, and Kristin Scott Thomas.

Three seasons later, the series has never been better. And showrunner Will Smith, one of Slow Horses‘ biggest fans, only plans to keep raising the bar.

“I think every season has to be better,” Smith told Decider in a Zoom interview ahead of Season 3’s finale. “There’s something about the show; there’s a magic to it. Everyone has a catalytic effect on each other and it’s just the sum of the chemistry going on. But I just knew when we first started it, just watching it on the monitors, it’s like I’m already watching the show. We haven’t edited. We haven’t put music on it. We haven’t graded it. I’m just watching the performances, and you could put that out… And I still have that now. I sit and I watch. And I get mocked for it, because I’ll sit and I laugh at stuff, and people are like, ‘OH, you’re laughing at work.’ I’m like, ‘No, I’m laughing at River, or Taverner for berating River, or I’m laughing at Lamb.’ They come alive for me.”

Adapted from Herron’s third book, Real Tigers, Season 3 saw MI5’s delightfully dysfunctional team of misfits uniting to rescue one of their own, while seeking a confidential file that could expose MI5 corruption at the highest level. With the stakes higher than ever before, the action-packed finale, “Footprints,” saw the Slough House crew engaged in several epic shootouts, conducting a Home Alone-style takedown complete with booby traps, and racking up the largest body count of the series.

When the end credits roll, fans will find themselves craving more Slow Horses shenanigans, which is perfect, since Season 4 is on the way. Once you’ve caught up on Season 3, be sure to read our chat with Smith about Season 3’s biggest scenes, some A+ Jack Lowden improv, River and Louisa’s new friends-to-lovers vibe, what’s in store for Season 4, Gary Oldman eating, and more.

Decider: Season 3 was superb. I really enjoyed the finale’s juxtaposition of this messy, large-scale action sequence interspersed with Lamb’s impromptu Home Alone traps, and a casual party bus through the house! How fun was it getting to bring those different scenarios to life?

Will Smith: Oh, it’s tremendous. When I started on it, I read all the books that were available at that point. And when I read this, I was like, “Oh my god, it’s basically a shootout and a Bond base. It’s a mixed Bond film.” So to get to do that was fantastic. And I’m so thrilled you enjoyed that, specifically the cutting of the big explosive stuff and the sneaky stuff, because that was like, “Oh, is that gonna work getting that in?” And then the bus was because the book had the bus. And obviously, it’s not cheap to do that. And it’s a very complicated stunt. And there was a point that was kind of like, “I mean, do we really need to do this?” We were like, “We absolutely have to do that bus moment.” And we did it. It’s just incredible because it was that’s one take.

Oh yeah, that’s the money take.

And then again in the edit, there was a lot of back and forth and cuts of like, how far do we go? Do we show him getting in the bus, or we just don’t see it? Is it out of nowhere, or are we giving away too much if we have too much of him? And so there’s a lot of graphic equalizing on that, and it’s great to hear it sounds like we got it right.

Definitely. I don’t know if you’re familiar with Severance —

Yeah.

This suspense and the cutting of all the different characters in this reminded me a bit of Severance‘s finale, which I also loved.

Yeah. I think if you could do that — that juggling of multiple heightened moments and everyone in parallel — if you get that right, it’s just, as a viewer, that’s what I love. So it was great to get to do that.

This is a big season for Standish, which culminates in a heartbreaking scene with Lamb at the gas station. They’re such phenomenal, versatile actors. But this felt like one of their greatest in-show performances, because they’re accessing these deep character histories and emotions. What was it like watching that scene come together, and can you tease anything about what the future holds for their relationship?

I mean, it was an utter privilege and a joy to watch them do that scene and to work on it with them. Gary had a lot of input and thoughts on how we were going to do that. He was like, “It’s like a couple at the petrol station. They’re just, they’re breaking up.” They just careen into a breakup they didn’t know they’re gonna have, and that’s what I love about it, is that this whole season is basically Lamb trying to get Catherine back, to save Catherine. And he gets her back and then loses her. There’s a very simple arc to that. And it’s just all the history that’s there between them — a lot of which she doesn’t know, that he can’t admit — all that pain and that trauma that he’s going through and she’s gone through. But you’re right. They’re two incredible actors drawing on such emotional reserves that all the thought and the sheer talent and experience that they bring that underpins their performance of those characters is on display in those scenes, because they care so deeply about the characters, they put so much thought into it. They become those characters. They’re both transformational actors. It was fantastic.

Can you blink twice if Roddy knows who killed Charles?

No, Roddy doesn’t know. [Laughs] Roddy has no idea about anything. Having him in the background, that was just an extra. It’s just such fun having him there. And in regards to the future for Lamb and Catherine, without giving too much of a spoiler, it’s very hard to imagine Slough House without Catherine. Lamb isn’t going to function well without her. Lamb needs Catherine.

Oh yeah, he’s barely functioning with her.

Yeah, you’re right. [Laughs] He’s not functioning at all. But if you enjoyed that scene, you’re going to enjoy some scenes in the next series. Put it that way.

Semi-related, the show is great at experimenting with different character pairings. This season we got a Ho and Lamb adventure. We saw Marcus and Shirley, who I love. And we got some powerful moments between Louisa and River. Jack Lowden is such an immense talent drama-wise, but also so funny. I was cackling when he went in for that car hug.

I think that’s one of my favorite scenes [we’ve] ever done, and full credit and praise to Rosalind Eleazar and Jack Lowden for that, because the original version, they pushed. They were like, “Oh, we think it could go deeper and it could be messier.” And so we just went back at it, and then they loved it. I mean, that hug was Jack. Because I remember I was actually there that day, and I remember Jack texted me going, “Yeah, I think it I think was alright. And I went for a hug. I’m not sure if it worked.”

It worked, Jack!

It worked so well because they navigate so much in that scene. There’s just his clumsiness. And there’s humor — there’s sort of cringe humor. “Oh my god, River. What are you doing?” And then the way she breaks down you just feel her trauma and her grief and then they come back together at the end and you just think that’s such a swirl of emotions to go through in a relatively short scene. I just love that we can do that, and I watched them and said, “Oh god, you’re just a different league, you two.” They’re just fabulous.

After that episode (Min, forgive me. Rest in peace.) I saw some online debates about whether or not River and Louisa had some vibes that could lead them to cross the friendship line in the future. We’ve seen the friends-to-lovers debate get pretty heated this year with Carmy and Sydney on The Bear. Can you speak to that at all?

Yeah, we’ve definitely played with that, I would say. And I think that comes from their performance, that comes from that hug as much as anything. And I think people would want to see them together, but all I could say is we’re going to be true to the character dynamics of the books. But it’s definitely — the question will not go unanswered. Put it that way. It’ll be in a Slow Horses way. And it will be messy. I can’t give too much away. 

Oh, I can’t wait. Another crucial relationship dynamic this season is between River and his grandfather. River tells Louisa he’s in the process of losing someone, which gutted me, and we see him start second-guessing and going against his idol. Jack and Jonathan Pryce are playing this so poignantly. Are those performances elevated even higher in Season 4?

Absolutely. They’re incredible. I mean, Jonathan doesn’t need to hear from me or anyone — he’s an absolute titan — but to watch Jack in scenes with Jonathan, you go, “Well, there’s no imbalance here. You guys are both bringing it.” That scene of them in the club is another one of my favorite scenes we’ve ever done. I was watching that like, “Oh my god.” I found it so moving and I can see the tenderness from Jack and the pain that Jonathan’s going through as he processes what has happened and realizes what’s happening to him. And that inspired me directly to go and write a scene for the end of Series 4, because I saw what they did, and I was like, “I know where we could go with that. I know what that can become.” I mean, they can do anything. They’re both in the range — it’s incredible. But it goes to a very heartfelt, very, very sad place and we continue to mind that in Spook Street, partly because that’s where the books go. That’s where this story goes. You know, the seeds that we’re sowing there lead directly into the events of Book 4, so there’s more of Jonathan and Jack in the next series and yeah, absolutely they reached new heights every time.

Do you know when we’re getting Season 4?

I genuinely don’t know. But I can tell you that it won’t be later than this time next year. So you won’t have to wait longer than a year.

OK, so we’ll have to think about that facial hair on Gary and River for a year. [Laughs] Gary Oldman said he’d be honored to wrap his career playing Jackson Lamb, and there’s certainly more source material to explore. In an ideal world how many seasons are you open to?

It’s really as many as Apple and Gary and the audience want. My only kind of personal feeling on that is that I would always want the last season to be the best. I think every season has to be better. You know, I wouldn’t want the last season to be the last season because people felt that it was past its prime or peaked and now there was nothing more to do. You really want to sort of go out on top. And that’s the challenge, is not to repeat and to feel it’s moving on, which the books do. And that’s the great thing. And I think that’s what the actors really enjoy, is that the characters — the ones who aren’t killed off — is that the characters kind of wear the scars of what happened in the previous books and previous seasons. They’re building. They’re developing. You’re tracking Louisa’s grief in losing Min and how she’s processing that. You’re seeing how Catherine is dealing with everything that she’s been through in the past. So there’s there’s always new things to be doing.

Dedicated Gary Oldman fans were delighted when Lamb said, “Who was it that said, ‘You can’t reason with a tiger when it has your head in its mouth,” because, of course, he played Churchill. I know in the past you included that “explaining Norway to a dog” line as a nod to The Thick Of It. Are you having a blast with all these references? And are there any others you’re particularly proud of or hoping fans would catch?

Yeah, the Churchill moment. [Laughs] The Churchill one was Gary. Gary suggested it, so I can’t take any credit for that. I mean, the only other ones are so small, probably not noticed by the wider audience, but I’m a huge fan of the band Marillion, and it’s one-time singer Fish, so occasionally there are references to band members. [Laughs] I mix up the names, so you don’t really know, but —

I love that you add that extra layer of complexity.

If we’ve got to make up a name for a character I’m like, oh!

(Note: Fish’s full name is Derek William Dick. Another Marillion member’s name is Steve Rothery. There’s a Slow Horses character named Derek Rothery. I’m obsessed. I need more.)

I want to ask about the unique role that music plays within this show. Obviously, there’s the iconic theme song, which should receive Succession-level praise in my opinion, and we have the Coldplay song in Seasons 1 and 2. But in Season 3 Shirley straight up kills a guy with a shard of an Elton John CD. Roddy does karaoke to Iron Maiden. And I laughed out loud when Shirley and Marcus were driving, listening to “Listen to Your Heart.” What goes into these perfect song selections?

It’s just thinking what is surprising and fun. Like I just thought it’s fun with Marcus, I don’t think you’d expect him to be an Elton John fan. So I was like, “That’s interesting!” Iron Maiden, that was me just thinking “What is a Ho song? How does he visualize himself?” And I can’t remember how I came across it. I was sort of familiar with some Iron Maiden, but once I found that, I was like “OK, that’s the song!” And it kind of feeds into him driving the bus through the side of the house. But it’s just a great insight into his mind. And then I think Saul Metzstein, our fabulous director, I think he would have done the car music there. Coldplay…Coldplay I’m really, really proud of, because it was thinking of a song — it’s a sort of joke in Season 1 — and I’m a Coldplay fan. It’s not anti- Coldplay. It’s just nobody wants to listen to the same song again and again and again. And then having that song play at Min’s funeral.

Yeah, I was like oh why am I crying to this song in 2022?!

Look, me too. I can not watch that — and this is where I sound like a crazy egomaniac — but it is genuinely because I watch the show as a fan. I know that sounds weird, and I can’t justify that. But from when I watched the first rushes of Ros doing that, even before the music was on, then when you put the music on I can’t watch that without welling up. And I think there’s something about the show, there’s a magic to it. Everyone has a catalytic effect on each other and it’s just the sum of the chemistry going on. But I just knew when we first started it, just watching it on the monitors and it’s like I’m already watching the show. We haven’t edited. We haven’t put music on it. We haven’t graded it. I’m just watching the performances, and you could put that out. That works. And I still have that now. I sit and I watch. And you know, I get mocked for it, because I’ll sit and I laugh at stuff, and people are like “OH, you’re laughing at work.” I’m like, “No, I’m laughing at River or Tavernar for berating River, or I’m laughing at Lamb.” They come alive for me.

Final question: If you could see Gary Oldman eat one food before the series ends, what are you choosing?

[Laughs] That’s a great question. Because the noodles was like, “What’s the most disgusting thing?” I mean, Gary, as you can probably imagine, he goes for it. He had 12 bowls of noodles and I don’t know how many ice cream cones he had. So we had that, we had chips, we’ve got kebab in this one. I’ve got some coming up, I don’t want to give you any spoilers, but now I’m thinking what would be the worst? Something with his fingers — 

Maybe something with a sauce that he could offensively wipe on…not a napkin.

Spaghetti bolognese with his fingers! [Laughs]

This interview was condensed for length and clarity.

Slow Horses Season 3 is now streaming on Apple TV+.