'Slow Horses' season 5: Everything we know so far

"Slow Horses" season 5 is officially my most anticipated show of 2025. Yes, technically that release date isn't confirmed but given there's already a trailer for season 5, I feel confident that we'll get new episodes next year.

This Gary Oldman spy thriller show remains an incredible hit for Apple TV Plus. Seasons 1 and 2 were beloved by fans and critics alike and season 3 was my pick for the best TV show we watched in 2023. Season 4 wasn't too far off the mark in quality either — if it wasn't for generational shows like "Shogun" and "Industry" it'd have retained its crown for another year.

Now that season 4 is over, you'll want to know what to expect in season 5. So here's everything we know about "Slow Horses" season 5, including the show's possible release date, the season 5 trailer, cast and plot speculation for the upcoming season.

'Slow Horses' season 5 release date speculation

Apple had already greenlit a fifth season of "Slow Horses" before the end of season 4. In fact, season 5 and season 6 have been officially approved by Apple (h/t Deadline).

For fans of the show, this isn't a surprise. The show is known for ending each season with a trailer for the following season, and sure enough season 4 ended with a season 5 trailer.

Furthermore, showrunner Will Smith has commented on the show's production schedule in the past, saying that typically there are three seasons of "Slow Horses" being worked on at any time. Typically, one is being written, another is being shot and a third is in post-production at any given point.

Given that season 5 has now wrapped filming according to Film Updates on Twitter (X), it seems like everything is currently on schedule. We predict "Slow Horses" season 5 will premiere in early September 2025 on Apple TV Plus.

'Slow Horses' season 5 trailer

Spoiler alert: Spoilers for seasons 1-5 of "Slow Horses" beyond this point

If you've seen "Slow Horses" season 4, then you'll have already seen the lone trailer we have for season 5 so far. But just in case you need a refresher, here it is below.

'Slow Horses' season 4 cast

"Slow Horses" technically only stars Gary Oldman as Jackson Lamb, Jack Lowden as River Cartwright and Kristin Scott Thomas as Diana Taverner. However, the show's ensemble cast beyond those stars is large and full of familiar faces.

We don't have an official cast yet for season 5, but here are our expectations for the full cast for season 5.

• Gary Oldman as Jackson Lamb, the washed-up spy in charge of Slough House, aka the "Slow Horses"
• Kristin Scott Thomas as Diana Taverner, the Deputy Director of MI5 who has a long history with Lamb.
• Jack Lowden as River Cartwright, one of Lamb's "Slow Horses" who is a relatively competent MI5 agent and was raised by his grandfather who was a former MI5 legend.
• Saskia Reeves as Catherine Standish, Lamb's former secretary and a recovering alcoholic.
• Rosalind Eleazar as Louisa Guy, one of Lamb's "Slow Horses" who is dealing with the trauma of a past relationship with a coworker.
• Christopher Chung as Roddy Ho, a member of Slough House who is a tech expert and incredibly annoying.
• Aimee-Ffion Edwards as Shirley Dander, one of Lamb's "Slow Horses" who has anger issues and a bit of a drug habit.
• Ruth Bradley as Emma Flyte, a newly introduced member of MI5 in season 4
• James Callis as Claude Whelan, Taverner's new boss at MI5.
• Tom Brooke as J.K. Coe, a British MI5 agent assigned to Slough House in season 4

'Slow Horses' season 5 plot speculation

Season 5 of "Slow Horses" has been confirmed to be an adaptation of Mick Herron's 2018 novel "London Rules." This is the fifth novel and sixth story in the "Slough House" series and is the sequel to "Spook Street," which was the basis for "Slow Horses" season 4.

I'm not going to go into full spoilers here — if you want to know everything that could happen, do some spy work and read the book for yourself. But here's a brief synopsis of what to expect in season 5.

Based on the season 5 teaser trailer and what happens in "London Rules," we know Ho and Lamb will be in some hot water in season 5. A series of terrorist attacks have finally come to the door of Slough House and it looks like our gang of misfits will need to dodge their share of bullets.

But season 5 won't be all about the action. The politics of the British government also have a role to play and that role should bring back Samuel West as populist MP Peter Judd. Unfortunately for season 4 newcomer and MI5 First Desk Claude Whelan (James Callis), the attacks and the ruthless world of politics may mean the end of his career.

Need a recap on what's happened in "Slow Horses" so far? You can stream seasons 1-4 again on Apple TV Plus.