Spoiler warning: This article discusses events through Slow Horses Season 6, Episode 1.
David Cartwright is dead when Slow Horses Season 6 begins. The premiere reveals that River’s grandfather died between seasons after his long decline with dementia, then makes his funeral the emotional center of “Circle of Life.” Jonathan Pryce’s departure follows the endpoint already built into David’s story rather than a reported behind-the-scenes dispute.
The distinction matters because neither Pryce nor the production has announced a clash, firing or scheduling problem. David also dies before the events of Joe Country, one of the two novels adapted this season. The series has therefore reached a source-material turn it spent several seasons preparing.
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- Release date: September 16, 2026
- Episode: Season 6, Episode 1
- Title: Circle of Life
- Genre: Spy thriller
- Streaming on: Apple TV
David’s long decline reaches its endpoint
David’s condition had steadily taken away the independence and sharp judgment that once defined the former senior MI5 officer. River eventually placed him in a care home, a painful choice that left both men facing the gap between David’s reputation as a legendary spy and his vulnerable final years.
Episode 1 does not treat that decline as a twist. It opens with River arranging a funeral whose public story cannot name David’s real career. His eulogy must honor a man who helped shape British intelligence while maintaining the cover that David worked in transportation.
The funeral leaves River exposed
The funeral also turns private grief into season-long plot. Jackson Lamb, Diana Taverner and the Slough House team gather as former agents are being killed. River’s estranged father, Frank Harkness, appears outside the church, tying David’s death to another unresolved part of River’s family.
Pryce still appears in a flashback to David’s final moments. The choice gives the character a goodbye instead of reducing him to a line of exposition, while keeping the premiere focused on River’s isolation after the person who raised him is gone. It also lets the episode separate David’s quiet death from the public ceremony built around his classified life.
Pryce’s exit serves the source story
There is no evidence that Pryce walked away because he was unhappy with the production. He has spoken warmly about the scripts, cast and directors. Barring a later flashback, the role ends because David’s death is part of the narrative the show has now reached.
David’s absence removes River’s anchor at the moment River becomes the assassins’ next target. That is the real purpose of the exit: Season 6 forces him to face Frank and the Slough House threat without the grandfather who shaped his identity. How do you think River will change without David? Share your view in the comments.
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