Gary Oldman and Kristin Scott Thomas in Slow Horses

‘Slow Horses’ Season 4 Release Window, Cast, Plot, and More

Fans of Apple TV+ spy thriller Slow Horses won’t have to wait that long to see their favorite group of MI5 rejects onscreen. The British series is expected to return with season 4 sometime around late November this year.

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The show has followed a pattern in this regard, as the last season was released on November 29, 2023, while the one before that arrived on December 2nd, 2022. Hence, the estimation of a late November/early December release shouldn’t be off by much.

In terms of cast, the show is sure to be back with Gary Oldman as Jackson Lamb, the head honcho of Slough House (a.k.a. Slow Horses). A rude but sharp individual, Oldman’s portrayal of a washed-up intelligence officer has captured both audiences and critics so far. Kristin Scott Thomas’ Diana Taverner is likely to be back as well, and so is Scottish actor Jack Lowden’s River Cartwright. Thomas portrays the role of a former deputy director and now head of MI5 (as things stand in the show). Lowden’s character is that of a competent agent who has been shoved into Slough House due to one unruly mistake.

Other members of the cast returning for season 4 are likely to be Rosalind Eleazar, Christopher Chung, Aimee Ffion-Edwards, and Kadiff Kirwan. Hugo Weaving is slated to play Frank Harness in season 4, the show’s likely antagonist. Ruth Bradley, James Callis, and Joanna Scanlan have also joined the roster for the new season.

The plot is confirmed to be based on Spook Street, the fourth novel in the Slough House saga. Written by Mike Herron in 2017, the book focuses on River Cartwright as he juggles his duty between being a responsible grandson and a secret service agent. Without going further into spoiling the plot, the show is also expected to witness a key death, as evidenced in the trailer.

Apple TV+ has already commissioned season 5, backing both creator William Smith and the rich source material. It won’t be surprising if the show is extended beyond that, as well, considering how well the viewers have responded to the three seasons.

(featured image: Apple TV+)


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Evan Tiwari
Evan is a staff writer at The Mary Sue, contributing to multiple sections, including but not limited to movies, TV shows, gaming, and music. He brings in more than five years of experience in the content and media industry, both as a manager and a writer. Outside his working hours, you can either catch him at a soccer game or dish out hot takes on his Twitter account.