Slow Horses fans have not one but two more exciting instalments to look forward to of this hit Apple TV+ thriller, as season 6 and 7 have been confirmed.

Slow Horses season 5 may have come to an end, but thankfully it’s not the end of the road for our five favourite spies and their curmudgeonly captain Jackson Lamb (Gary Oldman).

Here’s all the insider info on Slow Horses season 6, from the juicy plot and new and returning cast to when we can expect it on screens.

Is there a Slow Horses season 6?

Yes, there is a sixth season of Slow Horses coming to Apple TV+. The show was renewed for a sixth series back in October 2024, mere weeks after the season 4 finale.

In June this year, leading man Gary Oldman confirmed to Deadline that season 6 had already wrapped filming. He also revealed that the Slow Horses would be returning to film season 7 in late October, which was greenlit by Apple TV+ this summer.

As per previous instalments, season 6 will also be based on Mick Herron’s books: Joe Country (book six) and Slough House (book seven). Following the Slow Horses season 5 finale, viewers got a sneak peak at what we can expect from season 6 in a teaser trailer.

What’s the plot of Slow Horses season 6?

“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,” teases the official show synopsis for Slow Horses season 6.

In the season 6 teaser trailer, Jackson Lamb reveals that a man stole a top secret file that contained a list naming all of the Slow Horses. The man in question is now dead and subsequently Lamb’s “joes” are being hunted.

River Cartwright, Shirley Dander, Roddy Ho and JK Coe have their work cut out for them. And we see them chased and taken on by some anonymous assassins in the action-packed trailer.

There’s a chance that the assassins may be successful too (sob). Another scene shows Lamb, Catherine Standish and Diana Taverner present at a funeral.

Talking of Taverner, she’s clearly being blamed as Lamb tells her: “You got a leak Julian Assange would be proud of.” It also seems like her superiors are breathing down her neck to get the situation sorted asap. As Slow Horses newcomer Lucian Msamati bluntly tells her: “No one is unaccountable Diana.”

Amid the chaos and Slow Horses running for their lives, there’s also the return of a familiar face. Enter River’s dad Frank Harkness (Hugo Weaving). One scene shows father and son reunite and when questioned, Frank reveals he’s back for “business”. This can’t be a good thing, as season 4 revealed him to be head of a corrupt to-hire assassin squad, made up of his own army of sons groomed to kill.

Who returns in the cast of Slow Horses season 6?

All of your favourite faces are returning for the sixth season, including Oldman’s Jackson Lamb and Jack Lowden’s River Cartwright.

Other Slough House residents back for the next series are the no-nonsense Shirley (Aimee Ffion-Edwards), the monosyllabic JK Coe (Tom Brooke) and the ever-faithful ‘Standish’ (Saskia Reeves). Plus the love-him-and-hate-him Roddy Ho (Christopher Chung) who returns to his tech lair after spending most of season 5 incarcerated at MI5.

Now running the Park, as the newly promoted First Chair, is Diana Taverner (Kristin Scott Thomas). Head Dog Emma Flyte (Ruth Bradley) is also reporting for duty. Meanwhile, Molly Doran (Naomi Wirthner) has additionally returned to her position as the Park’s head archivist. This was after Lamb made Whelan hire her back last season.

While he doesn’t make an appearance in the trailer, we’re also expecting to see Jonathan Pryce back as David Cartwright, aka River’s grandad. He had an impressive career at MI5 and in the past has provided River with some handy intel and tips. But that was before he was diagnosed with dementia. He’s now living at a retirement home where River pays him a visit now and again.

Finally, viewers can also look forward to more from season 4 baddie Frank Harkniss. Actor Hugo Weaving confirmed his return to the show in November last year at the International Film Festival of India. “Each season generally is a book, but also each season departs a little bit from those books,” he said, explaining how his character was able to come back.

Who is new in the cast?

Am I being Unreasonable? breakout star Lenny Rush has joined the cast of Slow Horses season 6. He was spotted filming alongside Oldman in January this year. While we don’t know his character name, the season 6 trailer confirms he is the son of the man who leaked the Slow Horses names.

Rush is very much a rising talent. He bagged a BAFTA award for Best Male Comedy Performance in Daisy May Cooper’s BBC Three drama. He’s also appeared in Doctor Who and is signed on to star in Channel 4 festive drama Dear Father Christmas alongside Stephen Fry, Greg Davies and James Buckley.

Lucian Msamati is another new face in season 6. The actor is best known for his roles in Conclave, Hostage, Game of Thrones and Gangs of London. Last year, he starred in the West End production of Waiting for Godot alongside Ben Whishaw. From the teaser, it seems he is a senior figure at MI5 who will have a stern word with Diana Taverner.

Another new MI5 recruit is being played by Harry Lloyd, who instead seems keen to flatter Taverner. He played Viserys Targaryen in season one of Game of Thrones. He has also appeared in TV shows Marcella, The Fear, and Legion.

Finally, Poldark star Kyle Soller looks to be joining the cast as one of two new deadly assassins hunting the Slow Horses down.

How many episodes is it?

Slow Horses season six will comprise of six episodes in total, just like its previous seasons. Each one will be around 45-60 minutes long.

We’re expecting it to follow the same release schedule as season 5. So, instead of a boxset drop, one episode will drop weekly on Wednesdays on Apple TV+.

When’s the start date? How can I watch it?

There is currently no confirmed start date for Slow Horses season six. However, if the release follows the same pattern as seasons 4 and 5, we could expect to see the sixth instalment on screens in September and October 2026.

The Slow Horses team film two seasons at once. The sixth series has already been filmed, alongside season 5. What’s more, the cast and crew are currently gearing up to film season 7 later this month.

While you wait, you can rewatch Slow Horses seasons 1-5 on Apple TV+ with a qualifying subscription.

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Slow Horses seasons 1-5 are available on Apple TV+ now.