Slow Horses season 4: Release date and latest news

The events of this season are set to be adapted from Mick Herron's Spook Street, with some new characters including Tom Brooke's JK Coe and Hugo Weaving's Frank Harkness joining Gary Oldman's Lamb, Jack Lowden's river, Kristin Scott Thomas's Diana Taverner and the rest of the gang.

The season has only just begun, but fans wondering about the spy caper's future will be relieved to know it has already been renewed for season 5, with Oldman confirming filming was due to begin back in February, meaning it is not in the can – here's hoping for season 6 and beyond as well.

But for now, let's find out what else in store for season 4.

Slow Horses season 4 release date

Slow Horses season 4 landed on Apple TV+ on Wednesday 4th September, with the first episode debuting on the streamer on that day.

The remaining five episodes will now be released weekly until the finale drops on Wednesday 2nd October.

Slow Horses season 4 – who's in it?

Gary Oldman is back in the lead role as Jackson Lamb, with most of the ensemble joining him.

That 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).

Saskia Reeves is also be back as Catherine Standish, despite her character leaving Slough House at the end of season 3.

Meanwhile, new additions 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).

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

Behind the camera, Adam Randall (I See You) is on directing duties.

The full cast list for Slow Horses season 4 is as follows:

• Gary Oldman as Jackson Lamb
• Kristin Scott Thomas as Diana Taverner
• Jack Lowden as River Cartwright
• Rosalind Eleazar as Louisa Guy
• Christopher Chung as Roddy Ho
• Aimee-Ffion Edwards as Shirley Dander
• Kadiff Kirwan as Marcus Longridge
• Jonathan Pryce as David Cartwright
• Hugo Weaving as Frank Harkness
• Joanna Scanlan as Moira Tregorian
• Ruth Bradley as Emma Flyte
• Tom Brooke as JK Coe
• James Callis as Claude Whelan

Slow Horses season 4 plot: What could happen?

According to the official season 4 synopsis, the new instalment will open with "a bombing that detonates personal secrets, rocking the already unstable foundations of Slough House".

Aside from that, plot details about the show are being kept largely under wraps, but we do know that it will continue to draw from Mick Herron's books, with season 4's plot coming from Spook Street.

The blurb for the book 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."

Explaining what fans can expect from the plot of the new season, series creator Smith previously told RadioTimes.com: "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."

Is there a trailer for Slow Horses season 4?

Yes, a trailer for season 4 has now landed. You can watch the footage below:

Slow Horses seasons 1-3 are available to watch now on Apple TV+. Season 4 is streaming new episodes weekly – sign up to Apple TV+ now.

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