Slough House has never exactly been a place of peace, quiet, and functioning payroll. But “Circle of Life,” the Season 6 premiere of Apple TV’s Slow Horses, opens with a level of chaos that even Jackson Lamb’s crew of disgraced MI5 rejects might call excessive. There’s a funeral, a murder, a disappearing act by the entire department from MI5’s own database, and the unwelcome return of a man best described as River Cartwright’s personal nightmare. Welcome back, indeed.
If you’re catching up on what just happened, or bracing yourself for what Episode 2 has in store, here’s your complete, spoiler-filled breakdown.
A Very Quick Refresher: How Season 5 Ended
Before we get into the new season, let’s rewind. Season 5 closed out its adaptation of London Rules with MI5 in full meltdown mode. A Libyan terror cell was exploiting London’s political landscape and MI5’s own vulnerabilities to destabilize the city, with the mayoral race caught up in the wider chaos. The finale, titled “Scars,” picked up right after Tara had escaped custody and shut down MI5’s systems.
The fallout landed squarely on First Desk Claude Whelan, who tried to pin the department’s failures on Jackson Lamb, only for Lamb to blackmail him into resigning using a recording of Whelan’s own threats. Whelan didn’t survive the political fallout professionally he was forced out of the role and Diana Taverner finally achieved her long-standing ambition, stepping into the role of First Desk. In a phone call with Lamb after her promotion, Diana confirmed she wouldn’t be bringing River back to work at the Park, so Lamb simply said he’d keep him at Slough House instead, with his usual dry humor about needing a spare liver someday.
And then there was that final gut-punch. The season closed on Lamb, feet up on his desk, calling Diana to needle her about her promotion with the camera lingering on his badly scarred soles. A story Lamb had told earlier in the season, about an agent tortured and forced to watch his pregnant lover killed, turned out to be about him, not some anonymous “Joe.” One line delivered on the phone, and five seasons of “gruff, unlikeable slob” got a much darker backstory.
So heading into Season 6: Diana Taverner runs MI5, Claude Whelan is out, River is stuck at Slough House for good, and Jackson Lamb’s past is bloodier than anyone assumed. Not exactly a clean slate but then, this show has never believed in those.
Episode 1 Recap: “Circle of Life”
Struan Loy Gets a Very Bad Visit
The premiere doesn’t waste a second reminding you this is a show that treats its characters, even the minor and mostly forgotten ones, as fair game. We open on Struan Loy, remember him? Fired from MI5 all the way back in Season 1 for selling out Slough House now teaching martial arts out of a converted shipping container, which also doubles as his home, and dreaming of turning the containers into stackable tiny homes.
It’s a genuinely funny, slightly sad little character update, the kind of thing this show does better than almost anyone. Struan’s puffed up about his old MI5 days while teaching kids’ karate classes, telling them to always stay alert because enemies can strike when you least expect it, which is the kind of dramatic irony you can see coming from a mile away. Sure enough, a pair of visitors show up posing as investors interested in his shipping-container business idea, and Struan can’t figure out how they even heard about it; he never advertised it anywhere. Suspicion kicks in a little too late: the pair break his arm, lock him inside, and set the container alight, staging it to look like he simply couldn’t escape a freak fire.
A Second Body, and a List With River’s Name on It
The killers, later identified as a pair going by Jim and Jane, aren’t finished. They track down Kay White, another former Slough House employee we’ve never met before, at her home on a canal boat. In a scene played with the same chilling casualness as Struan’s murder, they knock her into the water and hold her under with an oar until she drowns, then calmly stroll away pretending to be a couple out for a walk whenever anyone passes by.
Two dead former Slow Horses stop looking like a coincidence fast and as Jim and Jane walk off from the canal, they run through their list of targets and land on a name: River Cartwright. Struan’s death gets filed as an accident, but Emma Flyte quietly hands Lamb the case file against Taverner’s wishes. It doesn’t take him and River long, once they inspect the burned container and find it barred shut from the outside, to realize someone is working through a list of former Slough House personnel on purpose.
Slough House Has Been Erased Literally
Back at Slough House, things are, somehow, worse than usual. As far as MI5’s records are concerned, Slough House no longer exists in the building and everyone in it has been completely wiped from the Service database, meaning nobody on the team is getting paid. Diana Taverner, now First Desk, even sends an estate agent around to appraise the property, unannounced a visit that ends with JK Coe introducing the man’s face to his keyboard. It’s petty, it’s absurd, and it’s exactly the kind of bureaucratic cruelty this show thrives on.
Catherine Standish goes digging and learns from Moira at the Park that the erasure wasn’t an administrative mistake it came down as a directive from the very top. That immediately puts Diana, as the new First Desk, under suspicion. But when Lamb confronts her directly, Taverner claims total ignorance, improvising an explanation on the spot. Whether that’s classic spy-agency deniability or she genuinely doesn’t know, the episode isn’t telling yet.
David Cartwright’s Funeral Becomes the Episode’s Emotional Center
The heart of the premiere, though, isn’t the murder plot, it’s grief. River is dealing with the death of his grandfather, David Cartwright, whose health had been declining for several seasons. Diana summons River to talk about funeral arrangements, and MI5 insists on maintaining David’s old Department of Transport cover story even in death, sticking rigidly to protocol. River, understandably, resents watching his grandfather’s memory get reduced to a paperwork exercise while he’s still actively grieving. Jokes from colleagues about him inheriting David’s fortune don’t help especially since most of that money went toward his care. On top of that, his estranged mother Isobel has been ignoring every attempt he’s made to reach her about the funeral.
Rather than take any real time off, River keeps showing up to Slough House while he’s grieving because apparently that’s easier than sitting with it.
The funeral itself becomes the episode’s central meeting point, pulling nearly every subplot into one churchyard. It’s where Peter Judd tells Diana about the mysterious offshore funding tied to last season’s attacks, where Jackson learns about another Slow Horse’s death from Roddy Ho, and where a bitter Diana reveals to Catherine that it was actually Jackson who killed her former boss, Charles Partner. Catherine had never known the truth, and she walks away from the graveside visibly shaken. That’s a bombshell dropped almost in passing, in the middle of a funeral which feels very on-brand for this show’s refusal to let any moment breathe without a gut-punch attached.
Meanwhile, Peter Judd tells Diana that the offshore money she seized after last season’s attacks didn’t belong to him but to an unnamed associate, someone the episode doesn’t identify. File that one away; it’s clearly going to matter.
As for River himself, he manages to hold it together long enough to deliver a eulogy that plays up David’s supposedly dull career at the Department of Transport, which sends Jackson into fits of laughter despite the solemn occasion. Peak Slow Horses: a moment of genuine sorrow undercut by Jackson Lamb cackling at a funeral. Somehow, it works.
The Ending: A Familiar, Unwelcome Face
Just when you think the episode’s done piling on, it saves its biggest gut-punch for the final scene. As the service ends, River spots a familiar face watching from a distance his estranged, dangerous father, Frank Harkness. River confronts him and chases him down, even climbing onto the hood of his car to stop him from driving off, but Frank slips away before any real confrontation happens. The episode never confirms why he’s back or whether he’s connected to Jim and Jane’s list; it’s left deliberately open, with River now on that list himself.
Refresher: Who Is Frank Harkness, and Why Does His Return Matter?
For anyone who needs the reminder: Frank, played by Hugo Weaving, is River’s biological father a former CIA operative turned mercenary who ran a private, illegal army using disgraced MI5 washouts as recruits. He was last outmaneuvered by River, then released once MI5 admitted it had previously used his illegal operation for covert missions of its own. He has leverage, and he knows it.
His reappearance, right as former Slough House agents start turning up dead, is hard to read as irrelevant but Episode 1 stops short of drawing any line between Frank and the killings. What it does give us is a loaded exchange: River notes that Frank’s operation was dismantled after Season 4, to which Frank simply replies, “There’s no setback that can’t be reversed.” Make of that what you will.
Slow Horses Season 6 Episode 2 Anticipation
Episode 1 left a stack of loose threads, and Episode 2, titled “Daddy Issues,” looks ready to start pulling at all of them at once. The official synopsis teases that the reemergence of Frank Harkness, combined with the suspicious string of murders targeting former Slow Horses, is going to put Lamb and the team on high alert.
A few things to watch for:
- Who is behind the attacks on former Slow Horses? With River now confirmed as a target, the hunt for Jim and Jane’s employer becomes urgent. Frank Harkness’s timing makes him an obvious theory, but the show has given us nothing solid to hang that on yet.
- Sid Baker is coming back. Long-time fans will remember Sid, and Olivia Cooke is confirmed to be returning to the role at some point this season which raises plenty of questions about how, and why, given the character’s history on the show.
- The offshore money mystery. Peter Judd’s mystery associate, the one who supposedly owns the seized offshore funds, is still unnamed. It’s a separate thread from the killings for now, but this show has a habit of tying its financial subplots to its body count eventually.
- Diana Taverner’s real motives. Her claims of ignorance about the database wipe leave Lamb visibly unconvinced, and the episode never confirms whether she ordered it herself. With Judd feeding her information at the funeral, her loyalties as the new First Desk are worth watching closely.
- River, on a list, with his father back. Between grief, an absent mother, a killers’ hit list with his name on it, and Frank skulking around his grandfather’s funeral, River has more than enough reason to do something reckless next episode.
Episode 2 is scheduled to land on Apple TV on Wednesday, September 23, 2026, keeping the show’s usual weekly release pace. Given how much “Circle of Life” set in motion in a single hour, next week can’t come soon enough.
The Bottom Line
Season 6 wastes zero time: two murdered ex-agents, an entire department erased from existence, a funeral that unearths one of the show’s darkest secrets, and a villain’s return that could unravel River all over again. It’s bleak, darkly funny in exactly the way this show does best, and it ends on a cliffhanger that makes waiting a week for Episode 2 feel genuinely unfair.
Slough House, as always, remains a terrible place to work. Which is exactly why it makes such great television.
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