‘Slow Horses’ Season 6 Release Schedule, Trailer, Plot, and Cast Explained

Apple TV is bringing back one of its most acclaimed dramas this fall, and fans finally have a full picture of what to expect. Slow Horses Season 6 premieres globally on September 16, 2026, on Apple TV, with a six episode run.

The new season shifts the show’s usual case of the week format into something more personal for Jackson Lamb’s team. Slow Horses has traditionally introduced a brand new case every season, with the Slough House team eventually saving the day by the finale despite being MI5’s rejects, but the Season 6 trailer signals a real departure from that formula this time around.

‘Slow Horses’ Season 6 Release Schedule

Slow Horses Season 6 will premiere globally on Wednesday, September 16 on Apple TV, with the season running six episodes total. After the first episode arrives, a new episode will be released every Wednesday until the finale on October 21.

Viewers hoping to pin down an exact hour will need to wait. Apple has not announced an official release time for the new season, and viewers should be cautious of unofficial reports claiming a specific hour until Apple confirms one. The safest approach is checking the app the morning of September 16 in whatever local time zone a viewer happens to be in.

The show remains locked to a single platform. ‘Slow Horses’ remains an Apple TV exclusive, and Season 6 will stream only on that service, alongside all five previous seasons, with no indication of a simulcast on another platform. Looking further ahead, the series already has more episodes in the pipeline. Season 6 will be followed by Season 7, which Apple TV has already confirmed, and the seventh season will be based on Mick Herron’s novel ‘Bad Actors’.

‘Slow Horses’ Season 6 Trailer Reveals a Major Return

Apple built anticipation for the new season with a two part rollout. On June 11, 2026, Apple TV shared a first look teaser for Season 6 on social media, and then on August 18, bosses shared a full trailer revealing Olivia Cooke’s return as Sid Baker.

That reveal carries weight for longtime viewers, since Sid was previously believed to have died in the first season of the series. The trailer ends with a look at her back and River spotting her, prompting Lamb to note that spies have all faked their own death at one time or another.

The footage also hints at how far the danger extends beyond any single agent. The trailer offers a look at anyone who has ever worked at Slough House being targeted, suggesting that Louisa Guy, who might have left for a new job, is being pulled back into the fold. In the trailer, Lamb is shown confronting Diana directly, with the stakes feeling personal based on the footage already released.

Critical goodwill toward the franchise has only grown heading into this release. According to Apple, all five seasons have a Certified Fresh score, with two seasons receiving a rare, perfect 100 percent critics’ score on Rotten Tomatoes, and the fifth season alone earned nine Primetime Emmy Awards, including a nod for Outstanding Drama Series.

‘Slow Horses’ Season 6 Plot Puts the Team on the Run

The new season pulls its story from two entries in Mick Herron’s book series rather than one. Season 6 is based on Joe Country and Slough House, the sixth and seventh novels in Herron’s Slough House series.

The central conflict starts with MI5’s Diana Taverner. The season sees the Slow Horses on the run as Diana Taverner throws them all into a fatally high stakes game of retaliation and revenge. The upcoming season will follow Jackson Lamb and his team of rejected MI5 agents as they go on the run when a hit list targeting everyone connected to Slough House triggers a bloody wave of assassinations.

Apple has kept most other plot specifics close to the vest ahead of the premiere. Apple’s official description keeps the plot details relatively limited, though the trailer footage already confirms the emotional core involves Lamb, Diana, and the returning Sid Baker.

‘Slow Horses’ Season 6 Cast Adds New Faces to Slough House

The returning ensemble covers nearly every familiar name from the series. Gary Oldman returns as Jackson Lamb, alongside Jack Lowden as River Cartwright, Kristin Scott Thomas as Diana Taverner, Saskia Reeves as Catherine Standish, Christopher Chung as Roddy Ho, Aimee-Ffion Edwards as Shirley Dander, Rosalind Eleazar as Louisa Guy, Tom Brooke as J.K. Coe, Jonathan Pryce as David Cartwright, and Hugo Weaving as Frank Harkness. Joanna Scanlan as Moira Tregorian, Samuel West as Peter Judd MP, and Ruth Bradley as Emma Flyte also return.

Several new performers join the show for the first time this season. Kyle Soller and MyAnna Buring appear as Joe and Jane, an assassin couple hunting down the Slough House agents who are being positioned as the season’s primary antagonists. Harry Lloyd joins as Damien Cantor, a media mogul and news channel owner, while Lucian Msamati plays Oliver Nash.

The most talked about newcomer, though, is a BAFTA winner making his ‘Slow Horses’ debut. Lenny Rush plays Reece Nesmith, described as a child witness pulled into the unfolding chaos. Apple has not published an official character description for Rush’s role, but advance coverage identifies Reece Nesmith as an eyewitness who crosses paths with both Jackson Lamb and Roddy Ho. Rush is already known to British audiences for ‘Am I Being Unreasonable?’, which earned him a BAFTA for male performance in a comedy programme.

With the countdown to September 16 now measured in days rather than months, the mystery of what exactly triggered this season’s hit list on Slough House feels like the question fans are most eager to see answered, and it is worth hearing which returning face, Sid Baker included, viewers are most anxious to watch walk back through Slough House’s door.