Slow Horses season 6: everything we know so far about the hit Apple TV+ show's return

Slow Horses season 6 has already finished filming, which is huge news considering season 5 isn't even out on Apple TV+ until September 24.

The gritty spy drama is getting a bit of a name for itself, not only for its thrilling action-packed scenes, but its incredible release schedule never leaving more than a year between seasons.

And it appears there's plenty more where that came from as Jackson Lamb and his team of down-and-out MI5 agents are returning for season 5, 6 and 7 over the next couple of years.

Adapted from the books by Mick Herron, Slow Horses season 6 already has a plot to follow and filming in the can, but there's plenty more to talk about when it comes to trailer, expected release date, predicted case, news, rumors and more. Though, I'll be sure to update here once season 5 hits Apple TV+.

Potential spoilers follow for Slow Horses seasons 1 to 4.

Slow Horses season 6 release date

Apple TV+ renewed Slow Horses for season 6 just days after the season 4 finale – and, according to Deadline, the cast and crew have already finished filming.

In an official statement from Apple TV+ on the show's renewal, Jay Hunt, creative director for Europe said: "Audiences around the world have fallen in love with the Slow Horses, and I'm delighted that Gary Oldman will be leading this star-studded cast on another acerbic and action-packed adventure".

So, when it comes to the Slow Horses season 6 release date, season 4 released in September 2024 and season 5 is scheduled for September 2025. With season 6's filming done and dusted, I think I can quite confidently say that season 6 is looking at a fall 2026 release date.

Slow Horses season 6 trailer: is there one?

Considering Slow Horses season 5 is yet to receive its own trailer, it seems incredibly unlikely that we'll get a season 6 trailer any time soon.

But, we were treated to a season 5 teaser look at the end of the season 4 finale. If that's the case this time round, mark October 22 on your calendar for the season 5 finale for a potential first look at season 6. I'll be sure to update here when it drops, too.

Slow Horses season 6 predicted cast

Full spoilers follow for Slow Horses season 5.

Slow Horses season 5 will air six episodes on Apple TV+ between September 24 and October 22. Since we don't know what happens yet (and we don't want to spoil it by revealing the plot of Mick Herron's 'London Rules' novel), we can only predict the cast to appear in season 6, with one known addition:

• Gary Oldman as Jackson Lamb
• 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
• Ruth Bradley as Emma Flyte
• James Callis as Claude Whelan
• Tom Brooke as J.K. Coe
• Hugo Weaving as Frank Harkness
• Joanna Scanlan as Moira Tergorian
• Jonathan Pryce as David Cartwright
• Lenny Rush as TBC
• Nick Mohammed as TBC
• Hiba Bennani as TBC

So, there's a new cast member that we know for certain is joining Slow Horses season 6 and that's Doctor Who's Lenny Rush who, according to the Radio Times, was spotted filming with Oldman in January. Other than that, I'm sure it'll be full of returning favorites.

Slow Horses season 6 potential plot synopsis and rumors

Major spoilers follow for Slow Horses seasons 1 through 4.

Slow Horses season 6 is confirmed to be the first season that will follow not one, but two, of Mick Herron's novels. As confirmed by Deadline, these will be 'Joe Country' and 'Slough House', the sixth and seventh books in the series.

And the official synopsis from Apple TV+ for season 6 is as follows: "Season six sees the Slow Horses on the run as Diana Taverner embroils them all in a fatally high-stakes game of retaliation and revenge".

To delve deeper into the plot, it's also worth taking at the synopsis's for the books. For 'Joe Country' that's: "In Slough House, the backwater for failed spies, memories are stirring, all of them bad. Catherine Standish is buying booze again, Louisa Guy is raking over the ashes of lost love, and new recruit Lech Wicinski, whose sins make him outcast even among the slow horses, is determined to discover who destroyed his career, even if he tears his life apart in the process.

"With winter taking its grip Jackson Lamb would sooner be left brooding in peace, but even he can't ignore the dried blood on his carpets. So when the man responsible for killing a slow horse breaks cover at last, Lamb sends his crew out to even the score.This time, they're heading into joe country. And they're not all coming home."

And for 'Slough House': "Slough House - the crumbling office building to which failed spies, the 'slow horses', are banished - has been wiped from secret service records.

"Reeling from recent losses in their ranks, the slow horses are worried they've been pushed further into the cold, and fatal accidents keep happening.

"With a new populist movement taking a grip on London's streets, the aftermath of a blunder by the Russian secret service that left a British citizen dead, and the old order ensuring that everything's for sale to the highest bidder, the world's an uncomfortable place for those deemed surplus to requirements.

"The wise move would be to find a safe place and wait for the troubles to pass.But the slow horses aren't famed for making wise decisions."

Much like the rest of Slow Horses, season 6 will also be six episodes long and while I'd usually take a look at the previous season to give an insight into the plot, it doesn't air until September/October.

I'll be sure to update here as soon as the story at Slough House has unfolded once more.

Will Slow Horses get more seasons on Apple TV+?

Slow Horses season 7 was officially confirmed by Apple TV+ in July and Deadline reported in June, whilst in conversation with Oldman, that "season 7 will begin shooting in the UK in late September or early October".

With season 5 following books 6 and 7 in Mick Herron's Slough House series, season 7 will follow 'Bad Actors'. There's also the soon-to-be published 'Clown Town' coming September 9, which could hint at at least one more season to come, but any news on this is unconfirmed.

But, there's also a Slough House spin-off series in the works titled Down Cemetery Road, based on Herron's first novel of the same name.

With filming already happening, The Hollywood Reporter revealed it will star both Emma Thompson and Ruth Wilson as Sarah Tucker and Zoë Boehm respectively.

Apple TV+'s creative director, Hunt, said of the news: "Down Cemetery Road has all the hallmarks of Mick Herron's funny and acerbic writing, and I'm delighted we will be bringing it to life for Apple TV+ with such a stellar cast".

For more Apple TV+ coverage, read our guides on Ted Lasso season 4, Foundation season 3, Presumed Innocent season 2, and Silo season 3.