'Slow Horses' Star Reacts to the Grim Episode 4 Twist That Changes Everything

Published Oct 7, 2026, 3:01 AM EDT

Carly Lane is an Atlanta-based writer and critic who has been with Collider in some form or fashion since 2021. She considers herself a television nerd, diehard romance/sci-fi/fantasy reader, and nascent horror lover. Her fondness of books is only eclipsed by the towering TBR that her shelves can't possibly contain.

She is the author of A REGENCY GUIDE TO MODERN LIFE: 1800s ADVICE ON 21ST CENTURY LOVE, FRIENDS, FUN AND MORE, published through DK Books (an imprint of Penguin Random House) and currently available wherever books are sold.

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Editor's note: The below interview contains major spoilers for Slow Horses Season 6 Episode 4.

Slow Horses has officially passed the halfway mark of Season 6, with the Apple TV spy thriller's latest episode culminating in a devastating gut-punch for our favorite MI5 misfits. Things have already been off to a rough start so far, with the agents of Slough House not only finding themselves wiped from MI5's internal systems, including payroll, but also in the sights of some deadly professional killers. While former Slow Horses are being killed off by the mysterious Russian assassins Jim (Kyle Soller) and Jane (MyAnna Buring), River Cartwright's (Jack Lowden) biological father, the ruthless mercenary Frank Harkness (Hugo Weaving), is also back in the picture for seemingly nefarious reasons — and he's not the only blast from the past who's just walked back into River's life. Sid Baker (Olivia Cooke), previously declared dead after the events of Season 1, is seemingly alive and well, pursuing her own investigation tied to a recent hit job in Russia — and has apparently become a target of Jim and Jane's as well.

When River and Sid's surprising reunion is cut short by their enemies' unflagging pursuit, they're ultimately rescued by the one colleague that Jackson Lamb (Gary Oldman) sent out to pick them up: J.K. Coe (Tom Brooke). The result is an initially hilarious reunion between two agents who forged an unlikely partnership last season, but Jim and Jane refuse to give up the hunt easily, with Episode 4, "Lost and Found," culminating in both Sid's kidnapping and the loss of a fan-favorite Slow Horse. Before premiere, Collider spoke with Brooke about the unscripted moments that ultimately made their way into Coe's storyline this season, what he enjoyed most about filming that brutal restroom fight with Soller, why Slow Horses author Mick Herron wanted Coe's fate to look different from the version in the book, and more.

COLLIDER: This season, you're not only reunited with Jack [Lowden] again, but you also get to have some scenes with Olivia Cooke. What stands out most in your memory about forming that unlikely trio with them this season? I was just watching the scene where River tries to take the front seat in Coe's car, and Coe offers it to Sid instead. "Manners!"

TOM BROOKE: I wrote it!

Did you?

BROOKE: Yeah. Because it was a very straightforward scene — get in the car, drive off — and I just thought, “It’s too juicy.” Coe's never met Sid, but he knows about her. So the first time we met was just before the scene, and I was like, “Look, we don’t have to do this at all, but what about this?” By that stage, three seasons in, Jack and I had done so much in Season 5; we were both like, “Yeah, let's do it.” Olivia was like, “This is great. Let’s do it!” We gave it to [director] Adam [Randall], and he was like, “Yeah, it's good. Let’s shoot it.”

And I was so pleased because she's so great. When Coe says, “Get in the front,” Sid really enjoys the fact that he's making River sit in the back. So that was my first day filming with [Olivia]. She’s lovely.

Tom Brooke Explains Shirley and Coe's Surprising Friendship in 'Slow Horses'

"... I think it really helps just open him up a little bit, bring him out."

Image via Apple TV

Shirley and Coe have a dynamic that's been quietly building in the background throughout the show, and so I was curious to hear about what you enjoyed about continuing to flesh out your unlikely partnership with Aimee [Ffion Edwards] this season.

BROOKE: We both noticed that Shirley gives Coe the gun at the end of Season 4, and then we're in the faith center at the end of [Season] 5, he slides her a gun. So when we started [Season] 6, there was a “what do you want to do this season?” sort of meeting, and I said, “We have both noticed that. I don't know what that is, but it's something.” So, I don't know, maybe that was why they put us together, but I'm glad that they went with it because I think it really helps just open him up a little bit, bring him out.

The scene at Blake's grave, Chris [Chung] was really ill that night, and he couldn't get to set. That scene was supposed to have Roddy in it, and he was in bed, couldn’t move. So, loads of the stuff we had to make up on the night. We were doing a take, and someone said, “Why does he get to be on his own?” And Gary [Oldman] says, “Because no one likes him.” And Shirley says, “I like him.” And it was such a moment. I thought, “Oh my God.”

It was really good because Adam didn't stay on me for very long for the reaction, which I think was really cool, because I couldn't help but smile. But what I really wanted was the smile in the toilet at the end with Kyle [Soller] to be the first and only time we see Coe happy.

Book readers know what Coe’s fate is as written by Mick [Herron], and the episode follows some beats, but it definitely changes the landscape in which his death happens. What were the early conversations like about concluding Coe's story this season and how closely you wanted to adhere to the book while doing something new for the show?

BROOKE: I was offered three seasons at the beginning, and when I read the books, I was like, “I understand why.” So that was fine. But the ending of Coe was so important that I think it was one of the first conversations I ever had with the showrunner, with Will [Smith], because I was like, “I want to do that. I want to make sure that's the end of the story. Hopefully, the arc will have been interesting enough to be able to pull it off.” And he was like, “Tom, this is Season 4. This will happen in years to come. Relax.” I was like, “I am relaxed, but we have to do it.”

Every season, I had it in my head that this was where we were going to end up. It was going to be Norway, and then it was going to be Scotland, and then it was a service station in Bakersfield, as is so often the way with filming. But it was just really important that that happened. Will said to me when we started that the books give us about four out of the six eps, so we have to find two episodes' worth of stuff. But Mick, from the off, was so up for it changing because, obviously, different medium, and also, he was very insistent that he didn't want just the same story. There are lots of different tweaks, and for this example, two books come together to make this season. Without Mick’s say-so, it would have been really different, but as it was, he just said, “Go for it.”

Tom Brooke Explains Coe's State of Mind About His 'Slow Horses' Fight Scene

"He knows who this person is. They are both killers."

Image via Apple TV

When I spoke with Kyle, he said that the line where Jim points out Coe's push knife was your idea.

BROOKE: Yeah.

As you mentioned earlier, that is the moment when we see that very telling smile from Coe. As much as they're almost mutually resigned to what has to happen, there's some respect under the surface, too. Kyle even likened it to the possibility that, in another life, these two men would go down to the pub and get a pint. What did you really want to emphasize about Coe's state of mind when he walks into that restroom? I think, at that point, he's already prepared for what has to happen.

BROOKE: Yeah, I think he is. I think he sees Jim coming when he's at the driving game. [Coe] knows the deal. He knows they're following him. For me, it was like he's acing it. Whether he means to or not, he's acing it. He's saved River and Sid, he's picked them up in the car, he’s done the bowling alley. They got away. Then he's driven out of a shootout, and he's done that. So, now he's in the mood for a chat, and I just think it's so typical of his oddness. But in the same way, I think it's quite logical. He knows who this person is. They are both killers.

I always had this idea that Coe was a psychopath because the more people he killed, the more human he felt — which is insane, but for him, that's what's happening. We see him at kind of peak Coe when we're in the toilet with him, because he's coming out of himself. So, at that stage, I was like, “Oh, I wonder what he'd be like if he wanted to chat.” And then obviously, you just go straight back to the books, and, “Oh, well, that's what he's like.”

When Kyle and I met, we did a fight rehearsal, and we read the scene together, just the two of us, and we added a couple of bits. I wouldn't have tried it other than the fact that I've seen him on stage a few times, and I'm such a fan. This guy's wicked. We had a great time in between the takes, giggling, screaming with laughter, and then, "Action." One of them ones. It was so nice. And weirdly, in another life, we do go for a pint now because [Kyle] lives less than a mile down the road. Yeah, I feel like a huge part of that scene was us getting on so well off-screen. Aimee said, “I called it. I knew you’d get on.”

As great as the fight sequence is, because it's so visceral and brutal and intense, the moment that feels most like a gut punch is River finding Coe already gone, with his earbuds in, which seemingly indicated that he knew he was dying and had just enough time to put them in. Was there ever a conversation about explicitly showing the moment when Coe passed, or was it always meant to be River finding him afterward?

BROOKE: Yeah. I always wondered if it was because he didn’t want to be alone, or he didn't want it to be quiet when he went. I don't remember them talking about, “Should we show it or not?” I remember in the book that he's found dead. You don't know he's dead until maybe River, maybe Shirley… I can’t quite remember who it is that finds him, but they get closer and closer and closer, and then they realize he's gone. So, I feel like that was in the air anyway.

But the moment that was really cool was Adam saying, “Could he be listening to music?” And I said, “Ahh, he can’t have his phone, because we’re dark, so it wouldn't make sense to have a phone on him. But do you know, what he did have in Season 1 was an [iPod] Shuffle.” And he was like, “That's it. That's what we use,” and then he suggested putting the music in a little bit, when [River] comes in the toilet. I haven't seen it, so I don't know. Is that in it?

You can hear the music very faintly coming through Coe's earbuds.

BROOKE: And the music was mad, as well, because Will once said to me, “What sort of music does [Coe] listen to?” I put my earphones in, and this hip-hop started, because I guess it was connected to my phone in some way. In [Season] 6, Adam was like, “What car does Coe drive?” And I was like, “An Audi or a Beamer. Something nice, because he’s got loads of money.”

Then I said, “I can tell you what he has on in the CD, as well.” And Adam is this mad hip-hop fan who once directed a video for a contemporary of the artist that I wanted to play the music from, so it was such a great, “Oh, we should definitely be doing this,” because we were both on board. It was such a fluke, but it was such a coming together that we were like, “This is a really good idea.” Little things like that. But in terms of the ending, basically, it was the book plus Adam that got us there.

New episodes of Slow Horses Season 6 premiere Wednesdays on Apple TV.