Slow Horses returned for its sixth season on September 16, when Apple TV released the first episode of a six part run. New installments follow each Wednesday through October 21. The series adapts Mick Herron’s novels about Slough House, a neglected corner of Britain’s MI5 where officers are sent after career missteps rather than being dismissed outright. Gary Oldman continues in the central role as Jackson Lamb, the department’s slovenly and sharp tongued leader.
The returning cast includes Jack Lowden as River Cartwright, Kristin Scott Thomas as senior intelligence official Diana Taverner, and Saskia Reeves, Christopher Chung, and Aimee-Ffion Edwards among the Slough House staff. Hugo Weaving and Rosalind Eleazar also return this season. Olivia Cooke rejoins the series as Sid Baker, a character who has been absent since the show’s early episodes, in one of the season’s most discussed additions to the lineup.
For the first time, a single season draws on two of Herron’s books, combining Joe Country and Slough House across its six episodes. The Slough House series has become a steady source of material for the show, which has kept close to the tone of the novels while condensing their plots for the screen. The decision to merge two books into one season reflects the pace at which the television version has moved through the original source material.
The new season places the Slough House team at the center of a campaign of retaliation, with past decisions and old enemies returning to threaten current and former members of the unit. As in earlier seasons, the story mixes bureaucratic infighting at MI5 headquarters with field work carried out by officers who are frequently underestimated. The show has built its reputation on that contrast between institutional politics and the efforts of its overlooked characters.
Slow Horses has become one of Apple TV’s most recognized dramas since its debut in 2022, drawing awards attention across its run. The series won an Outstanding Directing honor at the 2026 Emmy Awards and has been renewed for a seventh and eighth season, giving it a defined path forward. The sixth season arrives with the production already several installments ahead in development, drawing on Herron’s continuing series of Slough House books.
