Slow Horsesseason 4’s second episode picks up right where the premiere episode left — but first, it backtracks a bit to provide clarity aboutwhat really happened to River Cartwright(Jack Lowden). An adaptation of Mick Herron’sSpook Street, the fourthSlough Housenovel,Slow Horsesseason 4’s storyputs River and his grandfather, retired MI6 operative David Cartwright (Jonathan Pryce), in the middle of the action. In the fourth outing’s first episode,River contemplates moving his grandfather, who raised him like a son, into an elder care facility, so that he’s supported as his dementia worsens.
Slow Horsesseason 4, episode 1, “Identity Theft,“complicates these personal matters when a paranoid David kills a man.The intruder, who David fears is trying to impersonate River, might also have a connection to a recent car bombingat a London shopping center. Emma Flyte (Ruth Bradley), the new Head of the Dogs, calls Jackson Lamb (Gary Oldman) to the scene to identify River’s disfigured body. With Lamb’s confirmation of River’s identity, Flyte is tasked to track down David, who’s MIA. Lamb, meanwhile, follows his gut to Standish’s (Saskia Reeves) house, correctly guessing that both Cartwright men are alive.
7Slow Horses Season 4, Episode 2 Explains River’s Plan
River Arrives At David Cartwright’s House Just After The Murder
After chatting with Louisa Guy (Rosalind Eleazar) over some beers in the first episode of the season, River gathers his courage and pays his grandfather a visit. When River arrives, he finds David standing in the bathroom, shotgun raised. However, the addled expression on David’s face isn’t the most concerning matter — it’s the dead body in the bathtub and the blood spatter on the wall. River gets his grandfather to lower his weapon afterthe MI5 vet confirms his grandson’s identity by asking him something only River would know. While comforting David, River investigates his look-alike’s body.
…River wants to help his grandfather, especially since his uneven memory makes him a liability.
River walks his grandfather through a debrief — something David taught him to do — so that they can get their facts straight before calling in the incident. Although he’s not the most reliable narrator, David Cartwright gives a pretty accurate, though understandably frazzled, recap of the intruder’s time inside his home. After finding diazepam in the intruder’s pockets, River concludes that he was sent to kill David. However, the body contains other key information too. For starters,River finds an ID that reads “Adam Lockhead” and a return trip ticket to Lavande, France.
New episodes of Apple TV+‘sSlow Horsesseason 4 premiere on Wednesdays through July 14, 2025.
As River and David argue about what to do next,the elder Cartwright grabs his panic button and, against River’s wishes, presses it. “Now we’re on the clock,” River says in frustration. In one of the episode’s more emotional moments, the Cartwrights’ brief argument leads David to call River his son. Despite any momentary frustration, River wants to help his grandfather, especially since his uneven memory makes him a liability. After blasting the victim’s face with his grandfather’s shotgun and planting his own ID on the body, River takes David to another one ofSlow Horses’cast of characters: Standish.
6Jackson Lamb Questions David Cartwright
At the end of the season’s first episode, Jackson Lamb confirmed that River was alive after paying Catherine Standish a visit. Although Standish is no longer a member of Slough House in the wake ofSlow Horsesseason 3’s ending, she can’t give up the game. Not only is she looking into the shopping center incident, but she’s keeping David Cartwright hidden while River is away. In his typically abrasive fashion, Lamb questions both Standish and David.“He may be your grandson, but he’s my joe,” Lamb tells David, hoping the MI5 vet will scour his memory for helpful clues.
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Lamb goes on to explain that River shot his look-alike’s face off in order to buy himself some time. Gary Oldman’s character correctly guesses that River is pretending to be dead so that he can follow his lead with MI6’s involvement. While Standish and David are able to provide Lamb with some crucial information about River’s whereabouts, Lamb doesn’t figure out much about Lavande, France or how, exactly, River’s self-assigned mission might relate to the violent incident at the shopping center. Before he leaves in a huff,Lamb tells Standish to contact him if Cartwright remembers something significant.
5Giti Reveals To Taverner That MI6 Issued Robert Winters' Passport
Taverner Sends Giti Somewhere Safe
Meanwhile, at MI5, Diana Taverner (Kristin Scott Thomas) preps for yet another meeting that her superior, Claude Whelan (James Callis), should probably be taking the lead on. AlthoughSlow Horsesseason 4’s premiere episode reveals that Whelan landed the “First Desk” job over Taverner. Even so,the somewhat inept Whelan seems like the Director General of MI5 in name only. When it comes to the West Acres shopping center bombing and the subsequent investigation into Robert Winters, Taverner is calling the shots without consulting (or even briefing) Whelan. In the second episode, Taverner exerts even more control over MI5’s activities.
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Before Taverner leaves her office, she’s approached by Agent Giti Rahman (Kiran Sonia Sawar), who reveals some interesting information about Robert Winters' passport. Winters, Giti explains, has all the hallmarks of a real person, from a date of birth to a credit history, but his passport is peculiar. Evidently,the document was issued by MI5 several decades earlier. Taverner hides her reaction to the information well. After telling Giti to continue reporting to her directly (and cutting Whelan out entirely), Taverner calls Flyte to isolate Giti in a safe house so she can delve into the Robert Winters mystery.
4Jackson Lamb Enlists Moira Tregorian’s Help & Informs Slough House Of River’s Plan
Slough House Is As Dysfunctional As Ever In Slow Horses Season 4, Episode 2
When Lamb finally shows up at Slough House, the team is as dysfunctional and misinformed as ever. As Roddy Ho (Christopher Chung) continues to dismantle River’s computer, Lamb calls him out for not reading his text properly. While Lamb went to “identify” River’s body, he never said the younger Cartwright was dead. When Lamb jokes that the MIA River isn’t deadyet, Louisa expresses her frustration with the situation; like Lamb, Agent Guy wants to help River. Jackson Lamb insists thatSlough House’s emotional — and visible — reaction to River’s supposed death is a good thing.
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“You don’t blow a joe’s cover,” Lamb tells his team. This puts theagents of Slough Housein a tricky position when it comes to aiding River from afar without garnering suspicion from the rest of MI5. Still, Lamb shares that River is in France. Aside from the River drama, Marcus Longridge (Kadiff Kirwan) and Shirley Dander (Aimee-Ffion Edwards) get into a heated argument when Marcus reveals that he’s gambling again. Later,Lamb brokers a deal with Moira Tregorian(Joanna Scanlan),Standish’s Slough House replacement; Lamb knows she’ll do his bidding to claw her way out of Slough House.
3Diana Taverner Plots A Cover-Up Of The Robert Winters Cold Body
Taverner Also Blackmails Whelan Into Cooperating
Taverner calls Flyte and Giti at the safe house and reveals to the latter that what she uncovered earlier was all a big misunderstanding. Giti seems surprised to hear this, but the young, bright-eyed agent also wants to impress Taverner, so she goes with the flow. Taverner explains that there was a mix-up with the name on the passport — Robert Winters vs. Robert Winter. However, as she explains all of this,Taverner walks down a long hallway to a paper shredder of sorts and disposes of information relating to Robert Winters' identity, erasing his connection to MI5.
Taverner explains that Robert Winters is a Cold War-era “cold body” — one of many ready-made identities that MI5 would create for operatives.
Later, Taverner meets Whelan at a bus stop. MI5’s First Desk is incredibly jittery, revealing that he’s never worked in the field before. The duo board the next bus to have a private conversation; being in public, funnily enough, affords them some seclusion. Taverner explains that Robert Winters is a Cold War-era “cold body” — one of many ready-made identities that MI5 would create for operatives.When Whelan calls out Taverner’s cover-up scheme, she reveals that he unknowingly signed some paperwork relating to the sequestering of Giti. In short, Taverner blackmails Whelan into cooperating with her.
2Another Assassin Stops By The Cartwright Home To Plant A Camera
The Assassin Tells His Boss That River & David Are Both MIA
Back at the Cartwright homestead, an officer stands guard. Presumably, there’s some hope that David Cartwright will turn up at his house again, allowing MI5 to investigate what really happened the night River’s look-alike was killed. A man pulls up to the house, asking for directions. Although it’s clearly a ruse,the officer falls for the charade and gives the stranger some crucial information about the Cartwright men. Not only does the officer share that a younger man — supposedly River — was killed inside the house, but that the owner of the house, David, is still missing.
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On his way back to his car, the mysterious man stops at the stonewall lining David’s property, props his foot up, and pretends to tie his shoelaces. In reality,he’s planting a camera feed between the stones in order to keep an eye on the property, and, by extension, any remaining Cartwrights. Once he’s back in his car, the would-be assassin calls his boss, Frank (Hugo Weaving). The two men wonder if their colleague, Bertrand, was killed or if River was actually taken out. Before the call ends, Weaving’s character tells the assassin to go after another MI5 agent.
1River Discovers A Strange Compound In France
Hugo Weaving’s Frank Harkness Attacks River, Who Is Later Abducted By Another Stranger
When River arrives in Lavande, he discovers that the small town is unusually empty. Using his broken French, the Slough House agent asks around about Adam Lockhead — his look-alike. A café owner points River in the direction of a strange, palatial house near the woods. Although it’s supposedly abandoned, Lockhead might have some connection to the property. As River leaves the café,Slow Horsespauses on a mysterious character who’s clearly tailing River, though the man’s allegiances and motives aren’t yet clear. River soldiers on, climbing walls, pushing through overgrown hedges and breaking glass to enter a compound.
The bizarre objects hint at the fact that something deeply sinister occurred at the compound.
In an unsettling twist, the viewer knows that Hugo Weaving’s character is lying in wait for River as the determined Slough House agent investigates the massive home. Inside, River finds books about warfare, abandoned weaponry, and children’s prams and toys. The bizarre objects hint at the fact that something deeply sinister occurred at the compound.River finds a photograph, which features Weaving’s Frank and several other men on a hunting trip. Soon enough, River is attacked by Weaving’s character. Although he’s saved by the man who was tailing him, River is abducted at the end of theSlow Horsesepisode.
Slow Horses
Slow Horses follows a dysfunctional team of MI5 agents led by the notorious Jackson Lamb. Set against the backdrop of the espionage world, the agents must navigate complex operations and defend England from sinister forces, all while dealing with internal struggles and their abrasive boss.
