Slow Horses Season 6 now has an official release date and a full trailer, with Jackson Lamb and the Slough House team returning to Apple TV on Wednesday, September 16, 2026. The new season arrives almost a year after Season 5 and continues the increasingly dangerous story surrounding MI5’s most troublesome group of agents.
The newly released trailer also delivers a major surprise by confirming the return of Olivia Cooke as Sidonie “Sid” Baker, who has been absent from the series since its first season. Her unexpected appearance alongside River Cartwright immediately raises questions about what really happened to her.
Season 6 adapts Mick Herron’s Joe Country and Slough House, the sixth and seventh books in the series. The Slow Horses find themselves on the run after Diana Taverner pulls them into a deadly chain of retaliation and revenge.
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- Episodes: 6
- Premiere date: Wednesday, September 16, 2026
- Release schedule: One new episode every Wednesday
- Season finale: Wednesday, October 21, 2026
- Streaming on: Apple TV
- Starring: Gary Oldman, Jack Lowden, Kristin Scott Thomas, Saskia Reeves, Christopher Chung, Aimee-Ffion Edwards, Rosalind Eleazar, Joanna Scanlan, Samuel West, Ruth Bradley, Tom Brooke, Jonathan Pryce, Hugo Weaving, Lenny Rush and Olivia Cooke
Slow Horses Season 6 plot
Spoilers ahead for previous seasons and the Season 6 trailer.
Season 6 puts the Slow Horses in an unusually vulnerable position. The group appears to have effectively disappeared after sensitive information leaves them exposed, while Diana Taverner becomes involved in a dangerous game that forces Lamb and his agents to fight for their survival.
The trailer points toward a more action-heavy season, including fights, pursuits and renewed conflict involving River Cartwright and Frank Harkness. Hugo Weaving returns as Harkness after the character escaped at the end of his previous confrontation with River and MI5.
However, the biggest moment comes near the end of the trailer when River encounters Sid Baker. Olivia Cooke’s character was shot during Season 1 and later believed to have died, but the series never showed her death directly. Season 6 confirms that Sid survived, setting up a reunion that could have major consequences for River and the rest of Slough House.
FAQs
When does Slow Horses Season 6 come out?
Slow Horses Season 6 premieres globally on Apple TV on Wednesday, September 16, 2026.
How many episodes are in Slow Horses Season 6?
Season 6 has six episodes. Apple TV will release the premiere on September 16, followed by one episode every Wednesday through the finale on October 21.
Is there a Slow Horses Season 6 trailer?
Yes. The official trailer arrived on August 18, 2026 and shows Jackson Lamb and his team facing another dangerous MI5 crisis, while also revealing Sid Baker’s return.
Is Olivia Cooke returning to Slow Horses?
Yes. Olivia Cooke returns as Sidonie “Sid” Baker in Season 6 after last appearing during the first season. Her survival is revealed in the new trailer.
Has Slow Horses Season 7 been confirmed?
Yes. Slow Horses has already been renewed for a seventh season, so Season 6 will not mark the end of Jackson Lamb and the Slough House team.
All five previous seasons of Slow Horses are currently available to stream on Apple TV, giving viewers plenty of time to catch up before Season 6 begins on September 16. Apple TV costs $12.99 per month in the US, with a seven-day free trial available to eligible new subscribers.
What do you expect from Sid’s return and the next Slough House mission? Let us know in the comments.
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