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

Slow Horses season 5 is most certainly on the way. With filming wrapped on Apple TV+’s gritty spy thriller back in October, we're nearing ever closer — despite not having an actual release date, yet. But, while we wait for more action-packed scenes, gripping drama, and incredible acting, there's plenty to talk about when it comes to Jackson Lamb and his Slough House team's return.

The fact that Slow Horses has so far managed to release a new season every year is a wildly impressive feat in today’s streaming landscape and they’re clearly not stopping anytime soon. Season 5 is on the way, and there's already talk of season 6 filming. Here’s everything we know about it so far, including release date prediction, trailer, possible plot, news, rumors and more. Potential spoilers follow for Slow Horses seasons 1 to 4.

Slow Horses season 5 release date prediction

Apple TV+ renewed Slow Horses for a fifth season back in January 2024. And, in October, a X/Twitter post from FilmUpdates (see above) revealed season 5 had already wrapped production, just ten months after renewal.

To back this up, during an interview with Collider in October 2024, showrunner Will Smith said: “We've nearly done Season 5. We've got a couple of days to finish off on it, but we're already into the edit, so it's coming. Don't worry, it's coming. Not as quick as you want, but it's coming.”

When asked when it would be out, Smith replied: “I genuinely don't know the answer as to when it's gonna be out, but I can't imagine that Apple would want to leave it longer than a year since Season 4. So, the latest it would be out, I would say, would be the same slot next year.” And Apple certainly haven't left it longer than a year so far.

One of the best Apple TV+ shows has demonstrated an impressive release schedule, dropping a season every year since 2022 – and season 1 and 2 even came out in the same year. So, given that season 5 has wrapped production and was reportedly in edit in October, we’d make a release date prediction of mid- to late 2025.

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.

Given who we saw in the season 5 teaser, 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
• Rosaline 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

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.

With no sign of Jonathan Pryce (David Cartwright), Naomi Wirthner (Molly Doran), or Samuel West (Peter Judd) in the season 4 finale teaser and no mention elsewhere yet, we’re not sure if the'yll be reprising their roles.

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.

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."

With the book synopsis 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 we didn't see coming.

Will Slow Horses get more seasons on Apple TV+?

Slow Horses has already been renewed for season 6, 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.

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.