Since its debut, Slow Horses has quietly grown into one of the smartest, sharpest spy series on television. Adapted from Mick Herron’s Slough House novels, the show focuses not on MI5’s elite, but on its rejects — a group of misfit agents stuck in bureaucratic purgatory under the rumpled, brutally sarcastic watch of Jackson Lamb, portrayed by Gary Oldman in what many consider a career-defining role.
Over the first four seasons, we’ve followed these so-called “slow horses” as they stumble (and then succeed) through failed operations, political conspiracies, and deeply personal betrayals. What makes the series remarkable isn’t just the espionage — though it’s handled with cool precision — but its tone: part noir, part dark comedy, with an undercurrent of melancholy.
Season 4 left viewers on edge. A bombing, a hidden conspiracy involving River Cartwright’s grandfather, and a chilling new villain raised the stakes. But it also gave us a deeper look into the emotional costs of life in the shadows. Lamb remains a fascinating antihero — slovenly and cruel, yet fiercely protective of his team.
Now, let’s imagine where the story could go in Season 5, based on the next novel in the series: London Rules.
London is on edge. A string of bizarre, seemingly unconnected public attacks sends the capital into a frenzy. As MI5 scrambles for answers, Slough House is pulled in when evidence surfaces linking a former Slow Horse to the violence. As always, they’re not supposed to be involved — but they’re the only ones seeing the bigger picture.
River Cartwright struggles with loyalty to MI5 versus his conscience. Catherine Standish, haunted by past trauma, is drawn back into fieldwork. And Louisa Guy finds herself emotionally compromised by a connection to the prime suspect.
Meanwhile, Jackson Lamb discovers that the attacks are more than random acts of terror — they’re signals. Someone inside the British intelligence community is playing a long game, and it’s about to end in chaos.
Expect the usual biting dialogue, back-alley ambushes, and morally murky choices. Lamb’s verbal takedowns remain unmatched, while Oldman’s performance continues to swing between tragic and terrifying. With surveillance paranoia, extremist threats, and inter-agency sabotage, the new season will likely blend contemporary anxieties with old-school spycraft.
