Slow Horses Season 7 Adds Three Cast Members for 2027

Apple TV's espionage drama Slow Horses is preparing its next installment with three newly announced cast members and a storyline centered on a threat within the British government. Varada Sethu, Tuppence Middleton and Joshua McGuire have joined Season 7, which adapts Mick Herron's Bad Actors novel and is expected to continue the series' annual release pattern. The Hollywood Reporter reported the casting news on October 19, 2026.

Decider reported on October 21 that Apple TV had not announced an official premiere date, although a fall 2027 debut appears likely based on previous seasons' release schedules. The seventh season is expected to follow the show's established six-episode format. Its central conflict involves Jackson Lamb and his team of intelligence officers investigating a mole within the British government who threatens to destabilize the state, according to Apple TV's official season description.

The story draws from Bad Actors, the eighth full-length novel in Herron's Slough House series. The book follows a missing member of a government think tank tasked with limiting the intelligence service's independence, prompting former MI5 chief Claude Whelan to investigate.

The investigation leads back to Regent's Park, where Diana Taverner becomes a suspect. The narrative also involves Moscow's intelligence leadership and raises questions about how much Lamb knows about the developing situation. The season's preview, shown after the Season 6 finale, also points to unresolved tensions involving Russian intelligence chief Vassily Rasnikov. The character's arrival in the United Kingdom creates another potential confrontation for Lamb and his colleagues.

Season 6 adapted material from the sixth and seventh books in Herron's series and followed the Slough House agents as they faced assassins. Its finale, titled Judgment Day, ended with a dangerous cliffhanger, while the subsequent preview established the next season's government-focused investigation. The returning storyline also features Shirley Dander entering rehabilitation, Roddy Ho facing a dangerous situation and Taverner taking a more active role outside the office. The preview includes car chases, physical confrontations and warnings of a potentially large death toll, although the full circumstances remain undisclosed.

Slow Horses has maintained a relatively frequent release schedule since its debut. Season 1 premiered on April 1, 2022, followed by Season 2 on December 2, 2022, Season 3 on November 29, 2023, Season 4 on September 4, 2024, Season 5 on September 24, 2025, and Season 6 on September 16, 2026. Season 6 concludes its six-episode run on October 21, 2026. With Season 7's casting now reported and Bad Actors confirmed as its source material, the next major milestone is an official release announcement from Apple TV.