Olivia Cooke thought she was done with Slow Horses after Season 1. Her character, Sid Baker, took a bullet to the head and vanished. Five seasons later, she walked back into Slough House with two words: “Hello, River.” The return came with five weeks of night shoots, a pair of badly pulled thigh muscles, and a finale ending that left her co-star Jack Lowden face-down on a kitchen floor. Cooke spoke to Variety about all of it on October 21, 2026, the day after the Season 6 finale, “Judgement Day,” began streaming on Apple TV.
The Injury Came From Running, Not Stunts
Cooke expected the action scenes to be the hard part. Climbing fences, shooting weapons, standing on a moving truck while fire and gas canisters went off — none of it matched the damage caused by a simple chase.
“The one thing that actually did me in was just running. There’s a lot of scenes where I’m just running alongside Jack, who is twice as tall as me, and my 5-foot-5 arse is just desperately trying to keep up.” — Olivia Cooke, Variety
The scene was filmed around 2 a.m. Cooke had been standing still for too long before the cameras rolled. She set off after Lowden and felt both thighs give way.
“I pulled both of my quad muscles really, really badly. For two weeks, I was hobbling around. Just from a run!” — Olivia Cooke, Variety
Cooke joked that she should have called Tom Cruise’s team for advice on how to run on screen. The injury did not come from a stunt fall or a fight sequence. It came from trying to match pace with a taller co-star in the middle of a winter night shoot.
Five Weeks of Night Shoots in the Cold
Cooke’s entire Season 6 schedule was compressed into five weeks right before the December break. Every shoot happened at night, in the middle of winter. She described the experience as joyful anyway.
“It was just really joyous, even though we shot it right before the December break, in the middle of winter, all night shoots for five weeks, because they truncated all my stuff.” — Olivia Cooke, Variety
The tight schedule meant most of her work was with Lowden and director Adam Randall. Cooke compared it to making an independent film. Randall’s style on set was fast and flexible. If a stunt did not work or the set did not match the plan, he improvised.
“It did just feel like we were making an independent film for five weeks, because the majority of my stuff was just with Jack and Adam.” — Olivia Cooke, Variety
Why Sid Came Back Different
Sid did not return as the same cheerful agent from Season 1. Cooke had to rebuild the character from a darker place. Sid spent the missing years in a secret MI5 rehabilitation facility for former spies, learning how to walk and talk again.
“It’s been an incredibly lonely process that has, I think, cauterized a part of her.” — Olivia Cooke, Variety
Cooke said she asked Randall plenty of questions about what Sid went through. They imagined a facility somewhere like Cumbria — green, quiet, and easy to disappear into. The result is a version of Sid who is jaded, guarded, and slower to trust Diana Taverner (Kristin Scott Thomas), the MI5 chief who supposedly saved her.
The Cliffhanger That Ends the Season
Season 6 finished with River Cartwright (Lowden) walking into his late grandfather’s house to find Sid upstairs in the shower. He started making tea, changed his mind, and reached for a bottle of wine. Then his hand started to shake. He dropped to his knees, gasping for breath, and collapsed.
The poison was planted earlier in the season. In Episode 3, a Russian assassin coated a crowbar in the kitchen with a substance later identified as Novichok. River touched the crowbar in the finale without knowing.
Radio Times reported that Christopher Chung, who plays Roddy Ho, called it “the biggest cliffhanger that this series has ever done before.” Director Adam Randall told the outlet the quietness of the scene was deliberate.
“It’s almost the most wonderful happy ending. It’s sort of heartbreaking that it isn’t.” — Adam Randall, director, Radio Times
Gaby Chiappe, the show’s head writer, told TV Insider that River’s fate is genuinely open.
“People survive it, but people also die from it. So we don’t know what’s going to happen.” — Gaby Chiappe, TV Insider
The Showdown Cooke Wants With Kristin Scott Thomas
Sid and Diana Taverner never share a scene face to face in Season 6. Their confrontation happens over the phone. Cooke wants that to change.
“I hope so! I want a showdown. With Kristin Scott Thomas, I think she’s a wonderful actor. I could watch her endlessly. So selfishly, I want that for me, for my dear diary. But yes, it feels like that is a very cathartic thing that must happen.” — Olivia Cooke, Variety
Sid spent most of the season believing Diana saved her life. A phone call late in the season showed her that Diana had used her identity as cover for an off-the-books assassination and was willing to let her die. Cooke described Sid’s reaction as almost giddy — the relief of finally seeing the truth.
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What Olivia Cooke Is Doing After House of the Dragon
Cooke is heading into the final season of House of the Dragon, where she plays Alicent Hightower. She told Variety she wants to do theater once that schedule frees up.
“I really, really desperately want to do theater. I am trying. I’ve been trying for years to find the right thing.” — Olivia Cooke, Variety
She also said she wants to work on the other side of the camera. Cooke has been acting for 14 years, starting with Bates Motel and Me and Earl and the Dying Girl before Slow Horses and House of the Dragon.
Slow Horses has been renewed through Season 8. Season 7 is already in production. Apple TV has not announced a release date for Season 7.
Also Read: Slow Horses Season 6 Recap: Every Death, River’s Shocking Fate, and the Biggest Cliffhanger Yet
For more cast interviews and finale breakdowns from the shows everyone is watching, keep reading VvipTimes.
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