Slow Horses season 4: cast, plot and everything we know about the Gary Oldman spy series

Gary Oldman in Slow Horses
Gary Oldman in Slow Horses (Image credit: Apple TV Plus)

Quietly, Slow Horses has become one of Apple TV Plus' marquee TV shows, as the spy thriller that features plenty of wit is set to continue with Slow Horses season 4.

While Ted Lasso may have captured more attention, Slow Horses is already set to be one of the Apple TV Plus' longest-running original series to date, as in addition to season 4 the streamer has greenlit Slow Horses season 5, a number no other show has reached on Apple TV as of yet. So it seems that viewers have come to love Gary Oldman's Jackson Lamb and his team of misfit spies that are called upon again and again to save the day.

So for all those who can’t wait for the next Slough House mission, here is everything you need to know about Slow Horses season 4.

Slow Horses season 4 release date

We don't have an official release date for Slow Horses season 4, but we expect that the latest batch of episodes will arrive sometime in 2024.

This is based on the show's release pattern to date — the first two seasons arrived within eight months of each other in 2022 and then Slow Horses season 3 premiered in late November 2023 — and the fact that, as has become a tradition for the show, a teaser for the next season was included as part of Slow Horses season 3 finale, the new season is at least partially done filming, if not done entirely. 

We'll update this page when an official release date is announced. 

Slow Horses season 4 cast

Again, like the release date, an official cast list for Slow Horses season 4 hasn't been announced, but based on the teaser trailer we're able to confirm that all of the main cast appears set to return and a big name is joining the cast.

First off, Gary Oldman is set to reprise his role as Jackson Lamb, the brilliant but apathetic head of Slough House, one that has seen him receive nominations for Best Actor from BAFTA and the Golden Globes. Other members of Slough House returning for season 4 are Jack Lowden as River Cartwright, Saskia Reeves as Catherine Standish, Rosalind Eleazar as Louisa Guy, Christopher Chung as Roddy Ho, Aimee-Ffion Edwards as Shirley Dander and Kadiff Kirwan as Marcus Longridge.

Also set to reprise their roles from the first three seasons are Kristin Scott Thomas as Diana Taverner and Jonathan Pryce as David Cartwright. Whether or not other recurring cast members Sophie Okonedo and Samuel West also return is TBD.

As far as new cast members, the only one that we can be sure of right now is Hugo Weaving (The Matrix), as he appears in the trailer and seems poised to play the antagonist in season 4.

Slow Horses season 4 plot

All Apple TV Plus has shared about the plot of Slow Horses season 4 is the description that the season opens "with a bombing that detonates personal secrets, rocking the already unstable foundations of Slough House."

This latest season is likely adapted from Mick Herron's Spook Street book from his Slough House series.

Slow Horses season 4 trailer

Apple TV Plus hasn't made the Slow Horses season 4 trailer that was shown at the end of the season 3 finale available online, though some on the internet have posted it on YouTube and social media if you want to go and find it. 

How to watch Slow Horses

Slow Horses is an Apple TV Plus original series, so it is playing exclusively on the streaming service. If you want to watch Slow Horses seasons 1-3, you need to have a subscription to Apple TV Plus. 

Michael Balderston

Michael Balderston is a DC-based entertainment and assistant managing editor for What to Watch, who has previously written about the TV and movies with TV Technology, Awards Circuit and regional publications. Spending most of his time watching new movies at the theater or classics on TCM, some of Michael's favorite movies include Casablanca, Moulin Rouge!, Silence of the Lambs, Children of Men, One Flew Over the Cuckoos Nest and Star Wars. On the TV side he enjoys Only Murders in the Building, Yellowstone, The Boys, Game of Thrones and is always up for a Seinfeld rerun. Follow on Letterboxd.