Slow Horses season 5: everything we know so far about the popular Apple TV+ show's return

Slow Horses season 5 will arrive on Apple TV+ on September 24. In true Slow Horses fashion though, the gritty spy thriller hasn't made us wait too long between seasons.

And it appears there's plenty more action-packed scenes, gripping drama, and incredible acting on the way as Jackson Lamb and his Slough House team make their return.

Adapted from the books by Mick Herron, there's a lot more plot to unravel and a lot more seasons to do it over with the renewal of season 6 and 7 already locked in. For now, here’s everything we know about Slow Horses season 5 so far including release date, trailer, plot, confirmed cast and more.

Potential spoilers follow for Slow Horses seasons 1 to 4.

Slow Horses season 5 release date

Apple TV+ has confirmed a release date for Slow Horses season 5 – and it's September 24. Not only that, but the first two episodes will be premiering at the same time with the season consisting of six episodes.

No doubt this news will come as a huge relief for fans of one of the best Apple TV+ shows after Apple TV+ renewed Slow Horses for a fifth season back in January 2024. But, the wait is almost over.

Slow Horses season 5 trailer: is there one?

In what appears to be establishing itself as a Slow Horses tradition, there was a season 5 teaser trailer shared at the end of the season 4 finale.

In less than a minute, someone tries to kill Roddy, a terrorist plot threatens London, and once again, the police turn to Lamb to help them predict the next move.

Plus, an unknown killing, although if Slow Horses’ history is anything to go by, it could be anyone – no cast member is safe. We’ll get into more about what the teaser trailer alludes to when it comes to plot below, and we'll update here as soon as we have a full trailer to share.

Slow Horses season 5 confirmed cast

Full spoilers follow for Slow Horses season 4.

Thanks to an announcement by Apple TV+ combined with the teaser and first look images, here’s the confirmed cast for Slow Horses season 5:

• Gary Oldman as Jackson Lamb
• Jack Lowden as River Cartwright
• Kristin Scott Thomas as Diana Taverner
• Saskia Reeves as Catherine Standish
• Christopher Chung as Roddy Ho
• Aimee-Ffion Edwards as Shirley Dander
• Rosalind Eleazar as Louisa Guy
• Ruth Bradley as Emma Flyte
• James Callis as Claude Whelan
• Tom Brooke as J.K. Coe
• Hugo Weaving as Frank Harkness
• Joanna Scanlan as Moira Tergorian
• Jonathan Pryce as David Cartwright
• Nick Mohammed as TBC
• Hiba Bennani as TBC

Though Hugo Weaving's character, Frank Harkness, was not seen in the trailer, Digital Spy confirmed his return back in November 2024, while also suggesting Joanna Scanlan (Moira Tregorian) is expected to reprise her role, too. Though, no official word yet.

With no sign of Naomi Wirthner (Molly Doran) or Samuel West (Peter Judd) in the season 4 finale teaser and the Apple TV+ announcement, it's not clear whether they'll be returning for season 5.

Slow Horses season 5 potential plot synopsis and rumors

Major spoilers follow for Slow Horses seasons 1 through 4.

Slow Horses season 5 is confirmed to be an adaptation of Mick Herron’s ‘London Rules’ novel, the sequel to ‘Spook Street’ which acted as the basis for season 4.

To get a strong look at the possible plot for season 5 then, here’s the book’s official synopsis: “Regent's Park's First Desk, Claude Whelan, is learning this the hard way.

"Tasked with protecting a beleaguered prime minister, he's facing attack from all directions himself: from the showboating MP who orchestrated the Brexit vote, and now has his sights set on Number Ten; from the showboat's wife, a tabloid columnist, who's crucifying Whelan in print; and especially from his own deputy, Lady Di Taverner, who's alert for Claude's every stumble. Meanwhile, the country's being rocked by an apparently random string of terror attacks, and someone's trying to kill Roddy Ho."

Over at Slough House, the crew are struggling with personal problems: repressed grief, various addictions, retail paralysis, and the nagging suspicion that their newest colleague is a psychopath.

But collectively, they're about to rediscover their greatest strength - that of making a bad situation much, much worse. It's a good job Jackson Lamb knows the rules. Because those things aren't going to break themselves.”

From the season 5 trailer, we know that much of the show will stay true to the book. We also catch a glimpse of most of the main cast to confirm their return to Slough House, and there's an awkward kiss between River and Louisa that we're keen to unpack.

And in the official Apple TV+ announcement, there's even more insight into what will be unfolding this time round: "In season five of Slow Horses, everyone is suspicious when resident tech nerd Roddy Ho has a glamorous new girlfriend.

"When a series of increasingly bizarre events occur across the city, it falls to the Slow Horses to work out how everything is connected. After all, Lamb knows that in the world of espionage, the London Rules – cover your back – always apply".

Following suit with the previous seasons, Slow Horses always runs for six episodes with the plot spanning the events of two or three days. It appears with season 5, they’ll be sticking to this tried-and-tested method, as Smith spoke to Collider: “You feel if you stretch it beyond that — I mean, you can invent — I worry it would feel like padding, and it would take you away from what is great about the books. So, six, I think, is the magic number.”

In season 4, River met his biological father, Jack (Hugo Weaving), which only looked to strengthen his relationship with Lamb. But what about more from Frank? Well, the man himself spoke to Forbes, further confirming a reappearance: "You probably know that Frank is in one of the other books, and so the assumption is at the end of this season, and certainly to anyone who had read the books, is that Frank will be coming back.”

He adds: "Frank gets to play his Get Out of Jail Free card, which he has had all along because he knows that MI5 and David Cartwright tried to set him up. He knows he's got that, so he can say that fabulous line, 'I'll get the next train.' He can be that sort of a character because he actually is a survivor and excellently slippery."

Though, in an exclusive chat with Radio Times, showrunner Will Smith said there's one part of the book that won't feature: "In season 5, the challenge we had with that was Mick does a brilliant thing at the beginning where there's an attack, and he writes it, and you think you're somewhere in the Middle East, and then you reveal it’s Derbyshire, and that is brilliant. We cannot do that in the show."

But with confirmation of 'London Rules' and teaser trailer as a starting point, it's fair to say the core plot is etched out. But, for those who haven't read the books, and with the unique additions of the cast & crew, Slow Horses will undoubtedly bring twists and turns that you won't see coming.

Will Slow Horses get more seasons on Apple TV+?

Slow Horses has already been renewed for season 6 and 7, so yes there’s most definitely more to come.

As reported by Deadline, season 6 will be based on Mick Herron’s ‘Joe Country’ and ‘Slough House’ which are the sixth and seventh books in the series. Revealing: “In season 6, the spies head out on the run as Diana Taverner embroils them all in a fatally high-stakes game of retaliation and revenge.”

And it appears Gary Oldman has already finished filming his parts in season 6. During an interview with Deadline in February, when asked about the next, next season, he said: "I wrapped about two weeks ago." Though he said some of the other cast were still working.

While season 6 will take its plot from two novels, that leaves only one behind in the series. Well, that is until September, when Herron's ninth book 'Clown Town' is released.

And, according to Deadline, season 7 will "begin shooting in the UK in late September or early October".

In conversation with Gary Oldman, he added: "That is truly the wonderful gift that keeps on giving. I just adore the hell out of it, and the people. It is just such a wonderful thing really to be part of".

Furthermore, Smith adds that there’s interest from his perspective in a spin-off, “I do think, though, there’s a great book he wrote, the last book that came out, which is in the Slough House universe, and Slow Horses do come into it, which is called The Secret Hours. That could be a movie or a more limited number just because of the nature of that story.”

For more Apple TV+ coverage, read our guides on Ted Lasso season 4, Foundation season 3, Presumed Innocent season 2, and Silo season 3.