Slow Horses season six has earned glowing reviews from critics ahead of its return to Apple TV on September 16, with reviewers branding the new run of the MI5 spy drama as the best installment of the series so far.
The upcoming six-part series opens with a dramatic storyline as an unknown killer begins targeting anyone associated with Slough House, starting with the unexpected death of a familiar character in the opening scene of episode one.
Meanwhile, the surviving intelligence officers at Slough House are left dealing with unpaid wages after their paychecks are unexpectedly delayed. When team leader Jackson Lamb, played by Gary Oldman, investigates the disruption, he discovers that his entire department has been mysteriously erased from the official MI5 database.
The sixth season marks a key transition behind the scenes as screenwriter Gaby Chiappe takes over as head writer from original showrunner Will Smith. The new episodes adapt two books from author Mick Herron, drawing material from Joe Country and Slough House, which form the sixth and seventh novels in his acclaimed spy series.
Critics praise writing and new characters
Writing for The Times, reviewer Ben Dowell stated that series six "might just be the best yet, even if the mood is decidedly gloomy in Slough House." Dowell highlighted the show's balance of tension and humor, noting that "there is thrilling storytelling and some deftly applied comedy, and it’s always lifted whenever Oldman is on screen."
Dowell also singled out actor Lenny Rush for his performance as an "excellent new character" named Reece Nesmith. Rush joins a returning ensemble cast that includes actor Christopher Chung as technical specialist Roddy Ho.
Brian Tallerico of RogerEbert.com agreed that the new season "might be its best outing to date," praising the swift narrative pacing. Tallerico noted that "there’s no 6-episode anything on television this year that hums like the sixth season of Slow Horses, an outing that’s entertaining, suspenseful, and honestly moving."
Reflecting on the trajectory of the franchise, Tallerico added: "After season five, I was a little concerned 'Horses' was losing its cadence; now, I’m ready to watch it for another decade."
Back to back production and returning favorites
Writing for Decider.com, critic Nicole Gallucci observed that Apple TV's decision to film seasons back to back has maintained the high standard of the series. The production schedule allowed writers to develop scripts for upcoming episodes while earlier seasons were still in active production.
Gallucci stated that the series "consistently cements itself as one of television’s most compelling, high-quality shows," adding that coming less than a year after the fifth season finale, season six is "another masterpiece that raises the bar with sharp writing, standout performances, and deliciously dark humor."
Collider critic Carly Lane highlighted the decision to bring back established characters to reward long-term viewers. Lane noted that "Season 6's resurrection of past fan-favorites is one of the reasons it's both thrilling and surprisingly comforting to watch," explaining that the new episodes are "inextricably connected to some of the show's biggest moments to date."
Lane pointed out that while the deep narrative ties mean "viewers will definitely have to play catch-up on previous seasons rather than trying to jump in from a fresh starting point, it's a narrative choice that rewards the fans who have been devoted to the series since the very beginning."
Lane also commended actor Jack Lowden, calling his performance as agent River Cartwright "as terrific as ever to watch" and describing it as "one of his best-ever roles." Lowden has frequently been named by industry commentators as a leading contender to take over the role of James Bond in future films.
Background on Slough House and MI5
In a four-star review for The Radio Times, critic David Brown called the series "a high-wire act of laughs and thrills." Brown noted that "in its quieter moments, when grudges fester and Lamb abuses his underlings, Slow Horses remains the funniest workplace comedy on television."
Slow Horses is a British spy thriller television series based on the Slough House novel series by author Mick Herron. The drama focuses on an administrative branch of the Security Service, commonly known as MI5, located at Slough House away from the agency's primary Regent's Park headquarters. The department serves as a dumping ground for disgraced intelligence agents who have committed career-ending blunders.
The series stars Academy Award winner Gary Oldman as Jackson Lamb, the brilliant but notoriously unhygienic and cynical head of Slough House. The cast also features Oscar nominee Kristin Scott Thomas as Diana Taverner, the formidable deputy director-general of MI5 who frequently clashes with Lamb over departmental politics.
Original showrunner Will Smith developed the television adaptation for Apple TV, launching the first season in 2022. Under the stewardship of executive producers and writing staff, the series has earned multiple award nominations for its portrayal of British intelligence operations and workplace satire.
Release date and episode schedule
Viewers will be able to stream the first episode of Slow Horses season six starting September 16 on Apple TV.
Following the season premiere, new episodes of the six-part series will drop weekly on the platform until the finale on October 21.
