Slow Horses Episode Guide

River Cartwright joins Slough House after a disastrous training exercise destroys his promising MI5 career. When the department becomes connected to the kidnapping of a British-Pakistani student, its supposedly useless agents uncover an operation far more complicated than it initially appears.

Episode 1: Failure’s Contagious

Skull Face’s Pick

After failing an airport training exercise, River Cartwright is banished to Slough House under the abrasive Jackson Lamb. A tedious surveillance assignment involving disgraced journalist Robert Hobden takes on greater importance when a far-right group kidnaps student Hassan Ahmed.

Episode 2: Work Drinks

River discovers that colleague Sid Baker has been conducting an operation of her own, while Hassan’s kidnappers prepare their threatened execution. Lamb remains suspicious of the assignment given to his team and begins looking beyond the obvious extremist threat.

Episode 3: Bad Tradecraft

The situation changes violently when the operation surrounding Hassan begins to unravel. River, Min and Louisa are drawn into an unauthorised rescue attempt, while events at Slough House place Sid and Jed Moody in immediate danger.

Episode 4: Visiting Hours

MI5 security officers begin hunting Lamb’s team as Diana Taverner attempts to regain control of her compromised operation. With Slough House positioned to take the blame, its members must evade their own Service while continuing the search for Hassan.

Episode 5: Fiasco

Lamb and River infiltrate Regent’s Park to find evidence capable of exposing Taverner’s role in the crisis. Elsewhere, Standish and Roddy work to locate the kidnappers before their increasingly unstable leader carries out his threat.

Episode 6: Follies

Skull Face’s Pick

The slow horses and MI5 race separately to find Hassan before sunrise. As Lamb confronts the people responsible for the operation, River learns something unexpected about Sid and begins to understand just how completely the Service can erase one of its own.

The suspicious death of a former field agent draws Lamb into an old Cold War mystery involving Russian sleeper agents. River heads into the countryside while the remaining slow horses become involved in a questionable meeting with a supposed representative of a Russian oligarch.

Episode 1: Last Stop

Former MI5 officer Dickie Bow recognises someone from his past and follows him across London before dying under suspicious circumstances. Lamb refuses to accept the official explanation and discovers a message pointing towards an old Russian operation.

Episode 2: From Upshott with Love

River travels to the village of Upshott to investigate a possible sleeper agent, placing himself inside the life of the seemingly ordinary Tropper family. Back in London, Min and Louisa help Spider Webb prepare for a meeting with businessman Arkady Pashkin.

Episode 3: Drinking Games

Skull Face’s Pick

River’s investigation becomes increasingly personal as he grows closer to the Tropper family. Min follows a suspicious vehicle after the meeting with Pashkin, while Lamb attempts to determine whether the old Soviet cicada network ever truly disappeared.

Episode 4: Cicada

The team deals with the painful consequences of the previous operation as Lamb’s suspicions move closer to Nikolai Katinsky. River uncovers the identity of the active sleeper in Upshott, but doing so places him in considerable danger.

Episode 5: Boardroom Politics

Louisa and Marcus continue with the Pashkin meeting despite knowing that his organisation cannot be trusted. River discovers that the apparent terrorist target may be the Glasshouse, forcing Slough House to respond without waiting for Regent’s Park.

Episode 6: Old Scores

Skull Face’s Pick

Several apparently separate operations converge as the slow horses confront Pashkin’s people and an airborne threat approaches London. Lamb finally understands Katinsky’s true objective, leading both men back to unfinished business from the Cold War.

Catherine Standish is abducted by a private security team with a hidden connection to a murdered MI5 officer. River must break into Regent’s Park, while Lamb gradually discovers that the kidnapping is part of an attempt to expose a secret the Service is prepared to kill to protect.

Episode 1: Strange Games

A British intelligence operation in Istanbul ends in betrayal and murder. One year later, Standish disappears after an Alcoholics Anonymous meeting, prompting River to follow a set of instructions from her kidnappers.

Episode 2: Hard Lessons

River is ordered to steal sensitive information from Regent’s Park in exchange for Standish’s safety. Lamb investigates the kidnappers from another direction and begins to suspect that the apparent ransom demand is concealing a more substantial objective.

Episode 3: Negotiating with Tigers

The abduction is connected to a private security company conducting a test of MI5’s defences. As River learns that the exercise has a hidden purpose, Marcus and Shirley face Lamb’s anger over their handling of the crisis.

Episode 4: Uninvited Guests

Skull Face’s Pick

The slow horses enter a secure MI5 facility without understanding the full intentions of the people accompanying them. Lamb travels with Roddy to locate Standish, while rival factions at Regent’s Park begin manoeuvring against one another.

Episode 5: Cleaning Up

River and Louisa are trapped inside the facility as an armed assault team arrives with orders that leave little room for witnesses. Taverner and Tearney confront one another over the buried Footprint file, making the institutional stakes of the operation brutally clear.

Episode 6: Footprints

Skull Face’s Pick

Slough House mounts separate rescue efforts as River and Louisa fight to escape with evidence of an MI5 cover-up. Lamb saves Standish but must reveal a devastating truth about Charles Partner, while River decides whether protecting the Service is more important than exposing what it has done.

A devastating bombing at a London shopping centre leads back to David Cartwright and a secret buried within River’s family history. With a mercenary organisation eliminating evidence, River travels to France while Lamb protects Slough House from threats both outside and within MI5.

Episode 1: Identity Theft

A suicide bomber attacks the Westacres shopping centre, beginning an investigation into his carefully manufactured identity. Shortly afterwards, David Cartwright shoots a man claiming to be River, forcing Lamb to identify a body that raises more questions than it answers.

Episode 2: A Stranger Comes to Town

Lamb conceals his doubts about the dead man while River travels to France in search of answers. New Dogs commander Emma Flyte investigates David’s disappearance, and the recently arrived J.K. Coe quietly demonstrates that Slough House has acquired another complicated resident.

Episode 3: Penny for Your Thoughts

River’s search leads to Les Arbres, an isolated compound connected to a former intelligence operative. Lamb investigates the identities used by the Westacres bomber, while David’s deteriorating memory makes protecting him increasingly difficult.

Episode 4: Returns

Skull Face’s Pick

River uncovers a disturbing connection between Les Arbres, his mother and a group of trained assassins. Back in Britain, MI5 attempts to contain evidence linking the bombers’ false identities to past intelligence operations.

Episode 5: Grave Danger

Frank Harkness’s remaining operatives close in on River and David as Regent’s Park issues dangerous orders of its own. Lamb tries to keep the team alive while River is forced to confront what his grandfather sacrificed to protect their family.

Episode 6: Hello Goodbye

Skull Face’s Pick

River finally meets the man behind Les Arbres and learns why his family is central to the conspiracy. An attack on Slough House produces devastating consequences, while Harkness reveals that arresting him may be considerably more dangerous than allowing him to walk away.

A mass shooting begins a coordinated attempt to destabilise London during a bitter mayoral campaign. Shirley believes Roddy Ho is being targeted, but convincing anyone that Roddy has genuinely acquired a girlfriend proves almost as difficult as stopping the conspiracy.

Episode 1: Bad Dates

A gunman kills multiple people in Abbotsfield before being silenced by an unseen attacker. Shirley saves Roddy from an apparent attempt on his life and becomes suspicious of his new girlfriend, Tara, while Louisa prepares to take an extended break from the Service.

Episode 2: Incommunicado

Further incidents across London suggest that the Abbotsfield shooting was the opening move in a broader campaign. Roddy’s relationship with Tara comes under greater scrutiny, although his absolute confidence in his romantic appeal remains largely unaffected by evidence.

Episode 3: Tall Tales

Lamb recognises the attacks as stages in a strategy designed to spread fear, confusion and political division. The mayoral contest between Zafar Jaffrey and Dennis Gimball becomes part of the threat, forcing Slough House to protect two very different candidates.

Episode 4: Missiles

Skull Face’s Pick

Lamb’s team attempts to prevent attacks against the mayoral candidates while Claude Whelan struggles with a personal scandal. Tara’s connection to Roddy and the wider operation becomes clearer, placing MI5’s computer systems at serious risk.

Episode 5: Circus

Tara provides MI5 with information that appears capable of exposing the group behind the attacks. As Regent’s Park follows her instructions, Shirley and Standish uncover evidence that Roddy’s relationship has been manipulated from the beginning.

Episode 6: Scars

Skull Face’s Pick

With MI5 effectively blinded, the slow horses race to identify the final target of the destabilisation campaign. River receives unexpected help from his grandfather, Lamb fights to prevent Slough House from being closed, and an old story reveals something deeply personal about his past.

Season 6 is scheduled to begin on Apple TV on 16 September 2026, followed by one new episode each week. A seventh season has already been commissioned and will continue the Slough House story.