WARNING: contains MAJOR SPOILERS for series one and two of Slow Horses
We’ve said it once and we’ll say it again: Slow Horses is wildly underrated, and should be on the radar of anyone with an ounce of sense, especially if you’re a fan of slick spy thrillers and watching Gary Oldman at his multi-layered, cool, comedic best.
The first two episodes of Slow Horses series three (read our review here) are now streaming on Apple TV+, to be followed by weekly instalments all the way through to the end of the year. So if you’re thinking of dipping your toe in this Bond-with-attitude series, now’s your perfect opportunity to catch up with what happened in series one and two – and if you’ve already seen them but need a refresher, we’ve got you covered:
Meet the Slow Horses – and New Recruit, River Cartwright
Jackson Lamb (Gary Oldman) is the straight-talking, hygienically-questionable head of Slough House, the offices to which disgraced MI5 spies (also known as “slow horses”) get exiled to do menial grunt work in lieu of being fired. At the start of series one we meet the newest Slough House recruit, River Cartwright (Jack Lowden, Dunkirk), who ends up there after a training exercise he’s running goes horribly wrong.
The Big Players at MI5 HQ
MI5 is currently run by two kick-arse rivals: the cold and calculated Ingrid Tierney (Sophie Okonedo, Ratched) is in charge, with her second-in-command (also overseeing Slough House) the formidable Diana “Lady Di” Taverner (Kristin Scott-Thomas, Gosford Park). Alongside them is slippery character – and former friend of Cartwright – Spider Webb (Freddie Fox, House of The Dragon).
Lady Di’s Dodgy Off-The-Books Op
The slow horses find themselves embroiled in investigating a right-wing terror plot which involves a shady white supremacist organisation called The Sons of Albion kidnapping a Muslim student called Hassan and posting a video on social media announcing they’ll be beheading him the following morning.
Lamb discovers the plot is actually a set-up orchestrated by Taverner, and one of the supposed terrorists is an undercover former agent. But the plan goes horribly wrong when Diana’s ex-agent gets rumbled by his ruthless companions, and they chop his head off instead, before going on the run with their terrified hostage.
To save her own skin, Taverner tries to pin the blame for the operation on Slough House, so Lamb’s team then has a split focus: track down the terrorists to save Hassan, and stop Taverner getting Slough House shut down for good.
While Lamb foils Diana’s plan to frame him for the botched terror attack, River tracks down the terrorists and saves Hassan.
There’s More to River Cartwright Than Meets the Eye
We also discover that Cartwright’s failed training mission was another Taverner set-up, as she wanted him out of the way after discovering he’d seen her secretly meeting with the undercover agent she later installed in the right-wing terror plot, and has a photo to prove it.
This earns him a powerful enemy in Taverner, but he has a bit of an ace up his sleeve: his grandfather David (Jonathan Pryce, The Crown) is a former senior figure in MI5, which offers him a certain level of protection.
Lamb Hides the Truth About Standish’s Former Boss
Lamb has a well-concealed soft spot for his long-suffering secretary Catherine Standish (Saskia Reeves, Luther), who is a recovering alcoholic, still traumatised after finding her beloved boss – former Head of MI5, Charles Partner – dead in the bath from an apparent gun suicide.
We learn that Lamb looks after Standish because of his guilt at his own involvement in Partner’s death. It’s clear Taverner knows the truth – she hints at it to Standish throughout the series – but Lamb manages to conceal the real story from her.
The series ends with a minor bombshell twist: first, Lamb confesses to Standish that he’d bought Partner the gun he killed himself with, at his request, after he’d become paranoid that some former “unfriendly faces” from his time in Russia had resurfaced. But a flashback reveals that Lamb broke into Partner’s house, killed him, and staged the suicide – and he did this at the command of Cartwright’s grandfather, David.
The Russians Are at it Again
When ex-MI5 agent Dickie Bow is found dead of a supposed heart attack after following a suspected ex-Russian spy through London, Lamb suspects foul play. He finds a message on Dickie’s phone with one word – “cicada” – which was an old code word for Russian sleeper agents in the UK.
This – alongside testimony from Russian defector Katinsky, which confirmed the existence of the cicada operation – leads Lamb to believe these sleeper agents have now been activated for some kind of dangerous secret mission.
Shirley and Longridge: Two New Slow Horses
We meet Shirley (Aimee-Ffion Edwards, Peaky Blinders), who was exiled to Slough House because she attacked her case worker after he made inappropriate advances towards her, and Longridge (Kadiff Kirwan, This Is Going To Hurt), who is there because he has a gambling problem.
Alongside Lamb, Standish and Roddy Ho (Christopher Chung, Waterloo Road), they investigate Dicky Bow’s mysterious suspected killer, discovering he’s a former spy called Chernitsky, and after murdering Bow he ended up at a small airfield in a Cotswolds village, before seemingly vanishing.
River Goes Undercover
Lamb sends River undercover to investigate what Chernitsky was doing in the village, and he’s befriended by barmaid Kelly, and taken to dinner at her parents’ house. During dinner, their friend Leo arrives, but River recognises him as Chernitsky.
When he later tracks Chernitsky down to the airfield, River discovers that it’s actually Kelly’s mother Alex who is the sleeper agent, and she flies off with a plane full of explosives, heading towards an anti-capitalist protest in London.
Slow Horse Min Meets a Grisly End
Let’s back up a bit: in the meantime, slow horses Min (Dustin Demri-Burns) and Louisa (Rosalind Eleazar) are now a couple, after hooking up in series one. Away from the Chernitsky investigation, they’ve been recruited by Spider Webb to do an off-the-books security job for him, smoothing the ground for his meet-up with a Russian called Pashkin at a London skyscraper called The Glasshouse. Pashkin’s a representative of Nevsky, the powerful Russian who could one day replace Putin as President, so MI5 needs him on-side.
During Min and Louisa’s preparations for the meeting, Pashkin’s security team seem shifty, so Min starts following them around on his trusty bike, but then in a shock twist he’s found killed in a supposed hit-and-run. Lamb investigates, and discovers the hit-and-run driver’s links to Russia, and when interrogated she admits Min was actually killed by Pashkin’s security guards – alongside Chernitsky.
This confirms a connection between Spider’s meeting with Pashkin and the murder of Dickie Bow, and it also turns out the seemingly innocent Katinsky – Lamb’s Russian defector witness – appears to be at the head of the whole operation. Lamb later finds the oligarch Nevsky is dead of an apparent radioactive poisoning.
A devastated Louisa vows to get revenge on the Russians, but Lamb convinces her to go ahead with Spider’s original plan to meet Pashkin so they can work out exactly what their game is. Newcomer Longridge takes Min’s place in the security operation.
Power-Hungry Home Secretary Peter Judd
On the day of Spider’s meeting with Pashkin, there’s an anti-capitalist protest in central London, and Home Secretary Peter Judd (who we met in series one) is there making a speech, with Diana Taverner accompanying him as his security.
When River calls her to warn her about the plane full of explosives flying towards the protest, she evacuates the area and scrambles helicopters to intercept the aircraft – but it turns out the bomb plot was just a decoy to clear The Glasshouse and its surrounding area. The Russians’ real plan was a heist at The Glasshouse to retrieve Nevsky’s fortune, which the oligarch had stolen from Russia.
Diana and Judd agree to blame the unnecessary evacuation and costly interception of the plane on the current Prime Minister failing to upgrade MI5’s security systems, to help Judd’s bid to become PM.
It All Goes Horribly Wrong – and Spider Gets His Comeuppance
Back in The Glasshouse, Louisa and Longridge find themselves caught in the middle of the Russians’ real plan to drain Nevsky’s bank accounts, and when Spider discovers the truth he reacts so petulantly that Pashkin shoots him.
Louisa and Longridge eventually corner Pashkin with a bag full of diamonds on the roof of The Glasshouse trying to escape via a fake air ambulance, and Longridge shoots him dead, scattering the diamonds everywhere.
Spider survives, but his future in MI5 looks shaky at best.
One More Clue About The Death of Charles Partner
When Lamb confronts Katinsky about his and Pashkin’s plan, the Russian reveals he’d roped Slough House into their plot to humiliate Lamb, as payback for killing Partner. It turns out Partner had actually been acting as a double agent for the Russians, and this was why David Cartwright ordered Lamb to kill him.
Katinsky had also sent Chernitsky to kill David Cartwright, but River’s savvy grandfather was already onto him, and shot Chernitsky dead before he had a chance to kill him. With no hope left, Katinsky then shoots himself.
Slow Horses series three is streaming weekly on Apple TV+