‘Slow Horses’ Season 6 Release Schedule, Trailer, Plot and Cast
Jackson Lamb and his misfit MI5 rejects are back, and this time the danger feels personal. Apple TV has officially confirmed that ‘Slow Horses‘ Season 6 premieres Wednesday, September 16, 2026, with new episodes rolling out weekly through the finale on October 21 as the six-episode sixth season adapts Joe Country and Slough House, the sixth and seventh novels in Mick Herron’s Slough House book series.
The newly released trailer has already sent fans into a frenzy, and not just because of the explosions. The footage opens with Gary Oldman’s Jackson Lamb comically antagonizing his boss, MI5 First Desk Diana Taverner, played by Kristin Scott Thomas, before things take a darker turn for the entire Slough House crew.
‘Slow Horses’ Season 6 Release Schedule
Slow Horses Season 6 premieres globally on Apple TV on Wednesday, September 16, 2026. Fans hoping for a full binge drop will be disappointed, since the rollout follows the same weekly cadence the show has used since its debut.
The complete release schedule runs from Episode 1 on September 16 through Episode 2 on September 23, Episode 3 on September 30, Episode 4 on October 7, Episode 5 on October 14, and the finale on October 21. That gives viewers a two month stretch of weekly appointment viewing rather than a single weekend binge.
Apple has been coy about exact timing details. The streamer has confirmed the six episode count and the weekly release pattern from September 16 through October 21, but has not officially published individual episode titles or an exact release hour for the new season.
The new season arrives almost a year after Season 5, and ‘Slow Horses’ has notably kept an efficient schedule of filming seasons back to back, which bodes well for fans already anxious about a wait for Season 7.
‘Slow Horses’ Season 6 Trailer Breakdown
The trailer wastes no time setting up a mystery that feels different from previous years. Season 6 will see the Slough House team hunted by a pair of anonymous assassins, with several people linked to Lamb being killed off one by one.
Things get tense fast. Lamb orders his team to use a safe house and avoid using their phones as the threat closes in. It is a rare moment of real caution from a character usually more interested in insulting his agents than protecting them.
The biggest twist comes near the end of the footage. The trailer ends with a look at Sid Baker’s back as she surprises River Cartwright, with Lamb delivering the line that spies have all faked their own deaths at one time or another. Sid was shot during Season 1 and long believed to have died, though the show never actually showed her death on screen.
Critics have already noticed a shift in formula. ‘Slow Horses’ has traditionally introduced a brand new case each season with the team saving the day by the finale despite being MI5’s rejects, but the Season 6 trailer signals a real departure from that pattern this time around.
‘Slow Horses’ Season 6 Plot Details
The official logline promises a season unlike anything the show has done before. The Slow Horses find themselves on the run as Diana Taverner throws them all into a fatally high stakes game of retaliation and revenge.
Diana Taverner pulls the team into a dangerous situation involving retaliation and revenge, with Jackson Lamb remaining at the center of the story as the head of Slough House. As always, Apple has kept plot specifics tightly under wraps ahead of the premiere.
Sid’s return raises more questions than it answers. Her shocking comeback puts everyone connected to Slough House squarely in the crosshairs, especially with Louisa reportedly pulled back into the fold after possibly moving on to a new job. It sounds like nobody who has ever worked in that building is truly safe this time around.
Behind the scenes, there is also a changing of the guard in the writers room. Gaby Chiappe now serves as head writer after Will Smith departed the series following the first five seasons, with Ben Vanstone set to lead the writing team for Season 7.
‘Slow Horses’ Season 6 Cast
The returning ensemble reads like a reunion of everyone who has ever set foot in Slough House. Gary Oldman returns as Jackson Lamb, Jack Lowden is back as River Cartwright, and Kristin Scott Thomas reprises her role as Diana Taverner.
The supporting cast is just as stacked. Saskia Reeves, Christopher Chung, Aimee Ffion Edwards, Rosalind Eleazar, Joanna Scanlan, Samuel West, Ruth Bradley, Tom Brooke, Jonathan Pryce and Hugo Weaving all return for the new season, with Hugo Weaving reprising his role as Frank Harkness, River’s mercenary father.
Rosalind Eleazar returns as Louisa Guy, with her character coming back after previously leaving Slough House. Newcomer Lenny Rush also joins the ensemble, though his exact role remains undisclosed ahead of the premiere.
Of course, the headline addition is the one nobody saw coming. Apple confirmed Olivia Cooke’s return as agent Sidonie Sid Baker when it released the Season 6 trailer in August 2026, and her unexpected appearance alongside River Cartwright immediately raises questions about what really happened to her all those years ago.
With Sid Baker back from the presumed dead and the entire Slough House crew suddenly hunted by unseen enemies, ‘Slow Horses’ Season 6 looks primed to break its own formula wide open. Do you think Sid’s return is a miracle for River or a ticking time bomb for the whole team, and who do you suspect is really behind the attacks on Slough House?
