The sixth season of Slow Horses, Apple TV's acclaimed spy thriller, premiered on September 16, 2026, with episodes releasing weekly. This season, the show's trademark loser spies face a new threat: two emotionless assassins, played by MyAnna Buring and Kyle Soller, are systematically killing current and former MI5 agents—specifically those from Slough House that no one at the Park will miss. The only exception is Jackson Lamb (Gary Oldman), who considers them his losers.
A dual plot: Taverner's rise and fall
Concurrently, Diana Taverner (Kristin Scott Thomas) finally achieves her long-sought promotion to First Desk. However, her triumph is short-lived as she discovers a massive financial irregularity on the books that she cannot explain. Forced to defend herself, she gives an ill-advised TV interview on a right-wing station run by a stereotypical bad billionaire. As the season progresses, the two storylines converge, forcing Taverner to turn her attention back to the Slow Horses.
Despite the high stakes, this season doesn't quite click. The departure of showrunner Will Smith, known for his work on The Thick of It, may have contributed to a slight wobble in the dark tone. The season also faces the challenge of a sixth installment, balancing reinvention with crowd-pleasing, and it adapts two of Mick Herron's novels, which may have led to a somewhat muddled narrative.
Fan-favourite deaths and brutal tone
The tone is notably more brutal than in previous seasons. Several fan-favourite characters are killed, some in execution-style horror, and their surviving colleagues respond by avoiding eye contact and trying to forget. The season's humor also falls short, with fewer memorable one-liners from Lamb—nothing on par with 'Arsetime the Pope'—and many of the best quips already revealed in the trailer.
The return of Hugo Weaving's Frank Harkness is a mixed bag. While Weaving is less turgid and borders on charming, the ongoing conflict between Frank and River Cartwright (Jack Lowden) fails to accomplish anything new. The introduction of Lenny Rush as the bolshy son of one of the Dogs, who witnesses something incriminating, provides some distraction, though his dialogue feels like recycled Lamb material.
Performances and standout moments
Olivia Cooke's Sid Baker returns after a stint in a sanatorium, seeking out River for help and possibly more. Rosalind Eleazar's Louisa also stands out as one of the few characters capable of change, though Shirley (Aimee-Ffion Edwards) jealously nips at her heels in a beat that is played one time too many.
Despite the weak spots, the season remains a strong batch of episodes by regular TV standards. Jack Lowden delivers some of his best comic timing, sustaining numerous hand injuries that seem improbable to survive. Gary Oldman's Lamb remains grim but captivating, and Saskia Reeves' Standish is first-rate, dangerously close to relapsing or murdering Moira Tregorian (Joanna Scanlan).
Cliffhanger ending and future prospects
The season's biggest flaw is its ending: a cliffhanger that leaves viewers out in the cold for the first time. Even if the outcome seems predictable, it feels like a cheap send-off. Fortunately, Apple TV produces the show at a rapid pace, with filming on season eight already underway, so fans won't have to wait long to see how it resolves. The first episode of Slow Horses season 6 is available to stream on Apple TV, with subsequent episodes dropping weekly.
