What Did Frank Harkness Tell River About His Grandfather? Slow Horses Season 6 Ending Explained

What did Frank Harkness tell River Cartwright about his grandfather in the Slow Horses Season 6 finale? Their tense conversation reveals a disturbing side of Frank and leaves River with a new reason to question David Cartwright’s past. In this Slow Horses Season 6 ending explained video, we break down Frank and River’s final conversation, why Frank tells his son to investigate his grandfather, and what his cryptic words could mean for River’s future. Was Frank trying to help River understand his family, or was he deliberately leaving him with another mystery? We also explore Frank’s complicated feelings toward River, why he refuses to behave like a normal father, and how David Cartwright’s legacy continues to shape River’s life. The finale gives River a rare moment to confront his father, but the answers he receives may only lead to more questions. Plus, we examine how this conversation connects to the shocking final cliffhanger and what it could set up for the next season. What do you think Frank meant when he told River to look into his grandfather’s past? Share your theory in the comments! Subscribe to A Savvy Web for more Slow Horses ending explanations, character breakdowns, finale analysis, and theories about what happens next. #SlowHorses #SlowHorsesSeason6 #RiverCartwright