Jackson Lamb’s team of MI5 rejects is being hunted, and Apple TV+ is bringing the chase back to screens this week. “Slow Horses” returns for a sixth season on September 16, adapting one of the darkest books in Mick Herron’s spy series and putting nearly every Slough House agent’s life on the line at once.
Slow Horses Season 6 Release Date and How to Watch
Season 6 premieres September 16, 2026, exclusively on Apple TV+, with new episodes rolling out weekly every Wednesday through the six-episode run. The season finale is set for October 21, 2026. Apple TV+ requires a subscription, and the show has become one of the platform’s flagship titles since debuting in 2022, regularly cited as one of its strongest original series.
The Plot: A Hit List Targeting Slough House
Season 6 draws from Herron’s novels “Joe Country” and “Slough House,” and opens with a hit list circulating that names nearly everyone connected to the disgraced MI5 outpost. As agents tied to Slough House start turning up dead, Jackson Lamb is forced to figure out who’s behind the killings before his own team becomes the next targets. The season pulls the Slow Horses out of their usual paperwork purgatory and into a genuine fight for survival, with Diana Taverner’s own maneuvering at MI5 headquarters only making their situation more dangerous.
Diana Taverner’s High-Stakes Game
Kristin Scott Thomas returns as Diana Taverner, MI5’s ruthless deputy director, whose scheming has been a driving force behind the show’s twistier plots since season one. This season embroils the Slow Horses directly in a retaliation-and-revenge game tied to Taverner’s own maneuvering, blurring the line between the people meant to protect them and the ones putting targets on their backs. That dynamic has consistently been one of the show’s sharpest ongoing threads, and season 6 pushes it further than any prior run.
Olivia Cooke’s Surprise Return as Sid Baker
One of the season’s biggest cast reveals is the return of Olivia Cooke as Sid Baker, an agent believed to have died back in the show’s first season. Her reappearance is one of the more significant continuity twists in the show’s run so far, and it’s already generated plenty of discussion among longtime viewers about how the show plans to explain an apparent death that turns out not to have been final.
The Returning Cast
Gary Oldman leads the cast once again as Jackson Lamb, the brilliant, foul-mouthed head of Slough House, a role that’s become one of the most acclaimed performances of his career and earned him an Emmy nomination this year. He’s joined by Jack Lowden as River Cartwright, Saskia Reeves as Catherine Standish, and Rosalind Eleazar as Louisa Guy, who is pulled back into the fold this season after stepping away following a mental health break in season five. BAFTA winner Lenny Rush also joins the cast for the new season.
Why Slow Horses Keeps Getting Better
Few espionage dramas have managed to balance genuine tension with dry, cutting humor as consistently as “Slow Horses” has across five prior seasons, and that combination is a large part of why the show has become a critical favorite rather than just another spy thriller. Turning a hit list into the central engine of season 6 raises the stakes higher than the show has gone before, while still leaving room for the character-driven, slow-burn plotting that’s defined the series since its debut. For a show already sitting near the top of Apple TV+’s slate, a season built around this much direct danger to its core cast gives it a real chance to top itself again.
What Comes After Season 6
Apple TV+ has leaned on “Slow Horses” as a dependable anchor for its drama slate, and the weekly-release format for season 6 mirrors the rollout the show has used for its strongest prior seasons rather than a same-day binge drop. With Herron’s book series continuing well past “Slough House,” there’s no shortage of source material left if the show continues at its current pace, and a season built around a hit list targeting the entire cast leaves plenty of fallout for a potential seventh run to pick up, regardless of how many characters make it through October 21 in one piece.
FAQ: Slow Horses Season 6
When does Slow Horses season 6 premiere?
Season 6 premieres September 16, 2026, on Apple TV+, with new episodes releasing weekly through the October 21 finale.
What books is season 6 based on?
Season 6 adapts Mick Herron’s novels “Joe Country” and “Slough House.”
Is Olivia Cooke really back as Sid Baker?
Yes. Olivia Cooke returns as Sid Baker, a character believed to have died in season one.
How many episodes does season 6 have?
Six episodes, released weekly on Apple TV+.
For more on this year’s Emmy race, including Gary Oldman’s nomination, see ShowPulp’s 78th Emmy Awards coverage, and check out our OTT section for more streaming release dates.
More on the series is available on Wikipedia.
