Apple TV's 'Slow Horses' Is Officially Abandoning Its Original Formula With Season 6

Image via Apple TV Published Sep 3, 2026, 9:36 PM EDT Erin Konrad's love for everything entertainment dates back to elementary school when she became obsessed with classic Hollywood musicals. When she's not catching up on all her favorite television shows, she's advising her friends and family on what they should binge watch next. She has her Bachelor's degree in Journalism and a Masters of Fine Arts in Creative Writing. Creating content for Collider gives her the opportunity to combine her writing skills with her passion for television and movies. She spends her free time trying to beat her personal record of reading 137 books in a year and cuddling with her dog, Gracie. Sign in to your Collider account Anyone who has watched Apple TV's Slow Horses knows that it's one of the best shows on television. Over the last five seasons, the series has never failed to offer exciting storylines and fascinating characters that draw you in. With 30 episodes of high-stakes drama and a welcome dose of humor, there's never been a bad hour in the bunch. So, it might be a tad surprising to learn that Slow Horses is actually going to be switching things up a bit when Season 6 premieres on September 16. 'Slow Horses' Is Embracing More Serialized Storytelling in Season 6 So far, Slow Horses has introduced a brand-new case each season, as the titular team is presented with an unraveling mystery they'll need to solve. Despite being the rejects of MI5, the members of Slough House, led by Jackson Lamb (Gary Oldman), somehow always manage to save the day by the season's conclusion. This formula has been a tried-and-true aspect of the series, providing a clear structure for viewers to know they'll get a resolution if they stick it out through each six-episode season. However, a trailer for Season 6 reveals an intriguing change of pace for the spy thriller. Several characters will be returning, which gives Slow Horses a chance to continue storylines from past seasons. Notably, Louisa Guy (Rosalind Eleazar) seems to be back with her former Slough House colleagues. This is an interesting development, since many viewers wondered if Louisa would return after leaving MI5 behind in Season 5. Another returning face is Frank Harkness (Hugo Weaving), a villainous mercenary who terrorized London in Season 4 — and who also just so happens to be River Cartwright's (Jack Lowden) father. But perhaps Slow Horses' most shocking return is that of Sidonie "Sid" Baker (Olivia Cooke). In Season 1, Sid was shot in the head, and Diana Taverner (Kristin Scott Thomas) informed Slough House that she had died in the aftermath, but there was never specific confirmation of her actual death, and viewers later learn that all information about Sid has been erased from MI5 servers, as though she never existed in the first place. Her return not only promises some resolution about where Sid was, but also what's happened to her since the audience last saw her. Changing the Story Will Only Help 'Slow Horses' in the Long Run Bringing all these past characters back is a genius way to ensure that Slow Horses remains exciting and unpredictable. The move provides more context for devoted fans who have been watching and dissecting the show over the seasons while offering more in-depth narratives for the characters and the world in general. By embracing a more serialized storytelling approach, the show also becomes more complex, elevating it even further beyond a traditional spy thriller. There will still be a case to solve in Season 6, and it just might be the most significant one yet, as past and present Slough House agents are currently being targeted by an unknown group. This means that fans will get the best of both worlds between a threat connected to some of Slow Horses' best past seasons and a brand-new mystery to solve. Season 6 could feel different for several other reasons as well. Each prior season has been adapted from one of Mick Herron's bestselling novels, while the new season will draw material from two books. Creator and showrunner Will Smith has also exited the project, and Gaby Chiappe taking over as head writer has been another significant development for the series. With all these changes, it's clear that viewers are in for a different ride with Season 6, and with Season 7 already greenlit, that ride isn't ending any time soon. Seasons 1–5 of Slow Horses are available to stream in the U.S. Season 6 premieres on Wednesday, September 16. Slow Horses Release Date April 1, 2022 Network Apple TV+ Showrunner Douglas Urbanski