Apple TV+'s acclaimed spy thriller "Slow Horses" returns for its sixth season on Wednesday, September 16, 2026. In a departure from previous seasons, Season 6 will adapt two novels from Mick Herron's "Slough House" series: "Joe Country" and "Slough House."
New episodes will be available to stream at 9:00 p.m. ET the night before their official premiere dates. This means the first episode will be accessible Tuesday, September 15, at 9:00 p.m. ET. The season will consist of six episodes, with subsequent installments released weekly on Wednesdays until the finale on October 21.
The plot of "Slow Horses" Season 6 follows the disgraced MI5 agents as they are "on the run" following actions by Diana Taverner that embroil them in a high-stakes game of retaliation and revenge. The season's narrative draws from "Joe Country," the sixth book in Herron's series, which features Catherine Standish buying alcohol again, Louisa Guy revisiting past losses, and new recruit Lech Wicinski investigating the destruction of his career. It also incorporates elements of "Slough House," the seventh book, which portrays the agents feeling increasingly paranoid amid unusual deaths and a shifting political landscape in London.
Sir Gary Oldman returns as Jackson Lamb, the embittered leader of the Slough House spies. The cast also includes Kristin Scott Thomas as Diana Taverner, Jack Lowden as River Cartwright, Saskia Reeves as Catherine Standish, Rosalind Eleazar as Louisa Guy, Christopher Chung as Roddy Ho, Aimee-Ffion Edwards as Shirley Dander, and Tom Brooke as J.K. Coe. Notably, Olivia Cooke reprises her role as Sid Baker from the first season. New additions to the cast for Season 6 include Hugo Weaving as Frank Harkness, Lenny Rush as Reece Nesmith, Harry Lloyd as Damien Cantor, Kyle Soller as Jim, and MyAnna Buring as Jane.
"Slow Horses" has received critical acclaim, with Decider noting in its review of Season 6 that the show "consistently cements itself as one of television’s most compelling, high-quality shows." The series is available for streaming on Apple TV, which offers a seven-day free trial for new subscribers and a monthly subscription fee of $14.99. A bundle with Apple TV and Peacock is also available.
The series is based on Mick Herron's "Slough House" novels, which center on a group of MI5 agents relegated to administrative purgatory for various professional failures and personal blunders.