By Slow Horses’ own chaos-preferring standards, “Circle of Life” is a rather solemn start to the sixth season of the espionage drama. Also, it’s enough justification for why the show has been renewed for an eighth season.
Six seasons in, still knows exactly what kind of show it is, and "Circle of Life" leans with intention into that identity: bleak comedy stitched to real dread, delivered at quite a clip. The premiere wastes no time establishing the season's engine—former Slough House rejects are being hunted down one by one, and the episode's cold open makes that literal. Miserable Struan Loy, last seen way back in Season 1 and now running a children's karate school, gets a callback appearance that turns sour fast: two visitors show up at his home, and what begins as small talk about his post-MI5 life—shipping containers and their “stackability”—curdles into something unforeseeably violent.
This murder sets the tone for everything else. Inside the Park, Diana Taverner is settling uneasily into her new role as First Desk, trying to project authority she can’t quite claim yet, while Jackson Lamb—characteristically unperturbed by anyone else’s comfort— corners her over a pettier but symbolically loaded problem: the Slow Horses have been quietly erased from the Service's own systems, payroll included. Clearly, it's a very Slow Horses kind of indignity, using bureaucratic humiliation to signal a much bigger threat closing in.
Meanwhile, River Cartwright is dealing with grief that the show accords its due share of restraint: his grandfather David Cartwright has died, and the episode built around his funeral becomes the hub where several plot threads quietly intersect. It's also where the episode finds room for its best comic beats, even as the funeral itself is staged as the kind of flat, procedural send-off the Service reserves for its own. A cold institutional ritual. Lurking behind all of this is the reappearance of River's father, Frank Harkness, whose return is clearly tied to the season's central conspiracy, though the episode keeps his motives deliberately murky for now.
What I was impressed by is how season 6 handles its cast changes, new showrunner and character dynamics undergoing some amount of alteration—without losing the sardonic and shambolic messiness of its universe. No spoilers here, but the execution of another return to the cast from season 1 doesn’t come across as a stunt.
Taken together, you could call "Circle of Life" a controlled detonation—it doesn't waste time re-explaining who these characters are. It just starts picking them off and lets the paranoia do the narrative work. If the season sustains this hit rate, six years in, that's a genuinely rare thing for a spy drama to pull off.