Slow Horses season 4: Release date speculation, cast and latest news

Gary Oldman will of course be returning to his role as Jackson Lamb, while Jack Lowden will be back as River Cartwright. The rest of the central cast are also expected to return, while new cast members include the likes of Hugo Weaving (The Lord of the Rings), Joanna Scanlan (After Love), Ruth Bradley (Guilt), Tom Brooke (Empire of Light) and James Callis (Battlestar Galactica).

The series's creator Will Smith previously told RadioTimes.com that Weaving and Scanlon "were the absolute dream cast I had in my head when I first read the book before we even had a season 4 commission".

Explaining what fans can expect from the plot of the new season, he said: "I think that it continues the rupture that exists between River and his grandfather at the end of this season, where River finally starts to question his grandfather, he goes against his judgement, he starts to realise he's not the man he thought he was.

"And also, he isn't the man that he was in that he’s started to decline and he's starting to fall prey to dementia. It's following that through and seeing river having to deal with real issues, and face up to some things from his past and some things in his present that are really heavy for River to deal with.

"So River takes a battering, he’s losing some of his boyishness there."

So, just what is in store for the cast in season 4? Read on to find out.

*Warning - contains spoilers for Slow Horses season 3*

Will there be a Slow Horses season 4?

Yes! It was confirmed back in June 2022 that the series would be returning for at least a third and a fourth season, and that the new runs would be shot back-to-back just as seasons 1 and 2 were.

There could be even more instalments on the horizon, with season one director James Hawes previously outlining his hopes for further seasons, telling Deadline that "there is every hope and intention that there will be another couple of seasons in the immediate future".

Slow Horses season 4 release date speculation

Seasons 1 and 2 were released in quick succession, after being shot back-to-back, with the first season landing in April 2022 and the second in December.

There was then a longer hiatus between seasons 2 and 3, but with seasons 3 and 4 having also been shot back-to-back, this means we could see season 4 sooner rather than later.

We'd therefore expect season 4 to drop sometime in 2024, potentially in the first half of the year. We'll keep this page updated once anything gets confirmed.

Slow Horses season 4 cast

Gary Oldman will be back in the lead role as Jackson Lamb, while returns can also be expected for most of the ensemble, which includes Kristin Scott Thomas (Diana Taverner), Jack Lowden (River Cartwright), Rosalind Eleazar (Louisa Guy), Christopher Chung (Roddy Ho), Aimee-Ffion Edwards (Shirley Dander), Kadiff Kirwan (Marcus Longridge) and Jonathan Pryce (David Cartwright).

We'd also expect Saskia Reeves to be back as Catherine Standish, although her return is less certain after she left Slough House at the end of season 3.

Meanwhile, new cast members include Hugo Weaving (The Lord of the Rings), BAFTA winner Joanna Scanlan (After Love), Ruth Bradley (Guilt), Tom Brooke (Empire of Light) and James Callis (Battlestar Galactica).

Behind the camera, season 4 will be directed by Adam Randall (I See You).

Slow Horses season 4 plot: What could happen?

A press release has revealed that the fourth instalment will "open with a bombing that detonates personal secrets, rocking the already unstable foundations of Slough House".

Other than that, plot details for season 4 are currently pretty light on the ground, but we do know it will be based on Mick Herron's novel Spook Street, the blurb for which reads: "Twenty years retired from the Intelligence Service, David Cartwright still knows where all the bones are buried. But when he forgets that secrets are supposed to stay hidden, there's suddenly a target on his back.

"The 'Old Bastard' raised his grandson to be a hero, not a slow horse. Now, far from joining the myths and legends of Spook Street, River Cartwright is part of Jackson Lamb's team of pen-pushing no-hopers at Slough House. Which doesn't mean he won't ditch everything and go rogue when his grandfather comes under threat.

"Lamb worked with Cartwright back in the day, and knows better than most that this is no innocent old man. So when a panic button raises the alarm at Intelligence Service HQ, it's Lamb who's called on to identify the body. And it's Lamb who'll do whatever's necessary to protect an agent in peril."

Is there a trailer for Slow Horses season 4?

A trailer for Slow Horses season 4 aired at the end of the final episode, but so far it hasn't been released online. We'll keep this page updated and add it in once it has.

In the trailer, the team are seen responding to a bomb going off in London, and the threat of a second bomber. Meanwhile, Lamb says at the end of the trailer that one of his team has just died - but who?

Slow Horses seasons 1-3 are available to watch now on Apple TV+ – sign up to Apple TV+ now.

Visit our Drama hub for more news, interviews and features, or find something to watch now with our TV Guide or Streaming Guide.

Try Radio Times magazine today and get 10 issues for only £10 – subscribe now. For more from the biggest stars in TV, listen to The Radio Times Podcast.