"Slow Horses" season 4 has already come and gone. Yes, this means you can dive straight back into the action by streaming all six episodes right now.
The show has been a critical hit for Apple TV Plus and famously, each season ends with a trailer for the following season. Season 3 was no different. The third season of this British spy thriller was incredible — it was the best TV show we watched in 2023 — and, as is tradition, we got a trailer for season 4 at the end of the sixth and final episode of the season. And we know that we'll see a trailer for season 5 after the final episode of season 4 since Apple already greenlit a fifth season.
If that wasn't enough excitement, "Slow Horses" helped break the Apple TV Plus record with 9 Emmy nominations, including outstanding lead actor for Gary Oldman. That's right, this is now an award-winning show, and it deserves that recognition above any other Apple original.
So here's everything we know about "Slow Horses" season 4, including the show's episode guide, where you can watch it, and what you need to know about the ending.
'Slow Horses' season 4 episode guide and where to watch
The first episode of "Slow Horses" season 4 arrived on Apple TV Plus on September 4. This is earlier than we expected, but of course, no one is complaining. The big finale landed on October 9.
"Slow Horses" season 4 has 6 episodes to stay in line with the previous seasons, each around 40 minutes long. There are also some short bonus features you can watch on Apple TV Plus if you miss the show already (because who doesn't?).
Check out the full episode guide below:
- Episode 1, “Identity Theft” — Wednesday, September 4
- Episode 2, “A Stranger Comes To Town” — Wednesday, September 11
- Episode 3, “Penny For Your Thoughts” — Wednesday, September 18
- Episode 4, “Returns” — Wednesday, September 25
- Episode 5, “Grave Danger” — Wednesday, October 2
- Episode 6, “Hello Goodbye” — Wednesday, October 9
It's easy to keep little secrets… but dangerous to spill explosive ones.Slow Horses Season 4 premieres September 4 on Apple TV+ pic.twitter.com/gEueZhgqoeJune 27, 2024
Spoiler alert: Spoilers for seasons 1-4 of "Slow Horses" beyond this point
'Slow Horses' season 4 cast
Despite a now familiar ensemble cast, the show's main cast is a surprisingly small group. Gary Oldman's Jackson Lamb, Jack Lowden's River Cartwright and Kristin Scott Thomas's Diana Taverner are the only core members of the "Slow Horses" cast.
Here's the full cast for season 4:
- 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 former Deputy Director and now (presumed) head 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 secretary and a recovering alcoholic who seemingly leaves Slough House at the end of season 3.
- 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.
- Sophie Okonedo as Ingrid Tearney, dishonorable ex-head of MI5 who could appear in season 4
- Samuel West as Peter Judd, Conservative MP who could also appear in season 4
- Aimee-Ffion Edwards as Shirley Dander, one of Lamb's "Slow Horses" who has anger issues and a bit of a drug habit.
- Kadiff Kirwan as Marcus Longridge, one of Lamb's "Slow Horses" who has a serious gambling problem.
- Jonathan Pryce as David Cartwright, River's grandfather who was an MI5 legend but is slowly losing his mind.
- Hugo Weaving as Frank Harkness, likely season 4's main antagonist.
- Ruth Bradley as Emma Flyte, a newly introduced member of MI5.
- James Callis as Claude Whelan, Taverner's new second-in-command at MI5.
- Joanna Scanlan as Moira Tregorian, a British intelligence administrator
- Tom Brooke as J.K. Coe, a British MI5 agent currently assigned to Slough House
'Slow Horses' season 4 trailers
The first (very brief) trailer for season 4, which we see at the end of season 3, shows Jackson Lamb in a miserable state — not that he'd tell you. Meanwhile, a bomb has exploded in London and MI5 is in shambles. Emma Flyte (Ruth Bradley), appears as a new member of MI5 and is now seemingly a liaison between Slough House and MI5. MI5 is now led by Diana Taverner, and she's using Flyte to inquire about the state of Lamb's "rejects."
And then there's River Cartwright, who unsurprisingly is now stuck in another dangerous situation opposite a menacing Frank Harkness (Hugo Weaving) who either wants River to join him or die. As if that wasn't bad enough, he's also dealing with his grandfather's (Jonathan Pryce) deteriorating health.
UPDATE (August 16): Now though, we finally have a new explosive trailer for "Slow Horses" season 4. But after watching this latest trailer, the show's writers may have really cranked things up. I mean, it's obvious from the car bomb that explodes within the first 30 seconds.
This trailer is loaded with moments emblematic of what makes this show great. That includes classic comical scenes, like when River Cartwright (Jack Lowden) is trying to escape danger on the world's slowest bicycle. And of course, we have Oldman's Jackson Lamb, who ends the trailer with a ruthless comment.
Most of all, the trailer gives us a first look at the season's villain. Hugo Weaving plays the villainous Frank Harkness, who is a "monster that created a death squad in the past."
Check out the trailer:
'Slow Horses' season 4 plot summary (spoilers)
If you haven't yet watched "Slow Horses" season 4, it's best not to read on considering we're summarizing the entire season.
At the end of "Slow Horses" Season 4, significant developments unfold, particularly regarding River and the fate of several key characters. The season culminates with River facing a harrowing encounter with his estranged father, Frank Harkness. During a tense standoff, Frank takes River hostage but ultimately escapes by using a grenade as a distraction. A chase ensues, leading to Frank being arrested after River tracks him down at a bar.
In a dramatic twist, the season's climax also sees the death of Marcus, who is shot during an ambush orchestrated by Frank's son, Patrice. This moment is particularly impactful as it not only marks a significant loss for the Slough House team but also deepens the emotional stakes for River, who has just discovered his father's identity. Patrice is later captured and killed by J.K. Coe, bringing a violent end to the conflict.
The season concludes with the implication that Frank may be released soon due to letters threatening to expose MI5's past collaborations with him, leaving the future of several characters in a precarious state.
You can check out the short teaser for "Slow Horses" season 5 below:
