At a glance
Expert's Rating
Our Verdict
Slow Horses season 5 delivers plenty of high-octane action, while retaining the charm and character work that have made the show such a hit. Many of the cast members are given more to work with, expanding the show’s ensemble.
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The adaptation of Mick Herron’s Slough House novels, Slow Horses, has proved a smash hit for Apple, with season 4 proving far and away the most popular to date. The show’s fifth series sees our MI5 exiles facing some of their biggest challenges to date, in a race against the clock. With an ever-increasing audience, the challenge will be meeting fans’ expectations.
So, does the series stand up to the lofty standards of the previous seasons? I’ve seen the entirety of season 5, so keep reading for my spoiler-free review.
Season 5 of Slow Horses ups the stakes
Season 4 saw one of the show’s most memorable villains to date in Frank Harkness, a former CIA operative, hell bent on causing chaos for MI5 and Regents Park. It certainly helps when your villain is played by someone as dependable as Hugo Weaving (The Lord of the Rings, The Matrix). While there may not be a villain as compelling as Harkness at the heart of the fifth season, there is no shortage of carnage from this season’s “bad actors” to coin a phrase from Herron’s books.
We open with a shooting at Abbotsfield, a quiet London suburb, going about its daily business. The sense of calm is disrupted by a lone gunman, seemingly operating alone, but was he? How does this link to Roddy Ho’s new girlfriend, Tara, and the London Mayoral election? What ensues is a constantly escalating situation that threatens to spiral out of control very quickly. Of course, the slow horses aren’t far from the action.
The show switches things up
As ever, Will Smith, the mastermind behind the show’s success, brings Herron’s source material to life wonderfully. There are some slight alterations to certain character arcs and plot threads in this series. Rather than derailing the show, however, the changes feel natural and keep the show action-packed and full of suspense, while retaining the structure and core narrative of Herron’s novel, London Rules.
The challenge for the show’s writers has always been balancing the wit and humour, particularly of Jackson Lamb, the head of Slough House, never far from a scintillating one-liner or putdown. Others like James Callis’ Claude, the first desk of MI5, also bring their share of laughs. This is arguably the season with the most action, brilliantly choreographed and keeping the audience on the edge of the sofa.
Lamb continues to be a true delight on screen, with Gary Oldman once again delivering some dialogue for the ages and new mannerisms to go down in the show’s legend
Christopher Chung’s Roddy Ho has been in the show since day one but has felt on the periphery… until now. As with the book, Ho is at the centre of the action, allowing Chung to really flex his comedic and dramatic chops and prove why he has become such a fan favourite on both the page and screen.
The ensemble cast gets more involved
Spearheaded by Gary Oldman’s fart machine, Lamb, the show has had a key set of players with season 4 particularly revolving around Jack Lowden’s River Cartwright and his grandfather David (Jonathan Pryce). While Lowden is still a crucial cog in this season, it feels an ensemble affair very much, with the workload spread across the cast.
Other than Ho, another cast member to have a considerably larger role is Jk Coe (Tom Brooke), introduced in season 4; his role was largely on the fringes. Coe is key here in working out what the enemies of MI5 have planned, putting the skills he developed while working at the park to good use. Brooke is a more than welcome addition to the ever-expanding ensemble, a particularly enjoyable foil to the ambitious River, reeling from his grandfather’s ailing health and the aftermath of the events of the previous season.
There may not be any new slow horses in this season, but the cast expands with Nick Mohammed’s Mayor, Zafar Jaffrey. While Mohammed is best known for comedies like Ted Lasso, he proves here that he has more than what it takes to play it straight.
Lamb continues to be a true delight on screen, with Gary Oldman once again delivering some dialogue for the ages and new mannerisms to go down in the show’s legend. Kristin Scott Thomas’ Taverner, again, shines opposite Oldman, with her own schemes in play.
The issue for me is the sidelining of a couple of characters (for availability reasons), but this does not stop it from being another hugely enjoyable six-episode run
Should you watch Slow Horses season 5?
Fans of the show’s first four seasons and Herron’s books will find plenty to enjoy in season 5. It has all the action, humour and suspense we’ve come to expect from the team based out of Aldersgate without a drop in quality from the stellar previous seasons. The changes from the source material feel organic and help drive the plot forward, while retaining the essence of London Rules.
The issue for me is the sidelining of a couple of characters (for availability reasons), but this does not stop it from being another hugely enjoyable six-episode run. With the sixth season already filmed and a seventh on the way, we will see Lamb, Cartwright and co on screen for many years to come, with plenty more main series books and spin-offs for Apple to adapt.
Will Smith, who won an Emmy for his work on the show, is leaving after this season, and while that may raise an eyebrow from some fans, this is a fine way for him to bow out. Hopefully, the team taking over from him for season 6 and beyond can continue to bring Herron’s world to life in the same fashion.
If you feel a Jackson Lamb sized hole in your schedule once this season of Slow Horses finishes, fear not, the team behind this show are adapting Herron’s earlier novel Down Cemetery Road with an equally juicy cast including Emma Thompson and Ruth Wilson.
Slow Horses season 5 drops on Apple TV+ globally on 23 September 2025 – new episodes will drop weekly.
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Author: Chris Connor, Contributor, Tech Advisor
Chris Connor is a freelance film, TV and music critic whose work can be found in NME. Radio Times, Metro, IGN and more. He covers everything from espionage fiction to Star Wars, blending huge franchise films and indie releases and is especially keen on world cinema.