The critically acclaimed espionage thriller “Slow Horses” returns for its highly anticipated fifth season, premiering exclusively on Apple TV+ on September 24, 2025. Based on Mick Herron’s bestselling novel series, the show continues to follow the misfit agents of Slough House, MI5’s dumping ground for disgraced intelligence officers. These “slow horses” are relegated to mind-numbing paperwork and dead-end cases, yet they consistently find themselves thrust into the heart of dangerous conspiracies that threaten the United Kingdom’s national security. The series masterfully blends gritty, high-stakes spy drama with sharp, character-driven wit and suspense.

This season, the dysfunctional team must once again navigate a treacherous landscape of political machinations, internal betrayals, and external threats. Led by the brilliantly crude and cunning Jackson Lamb, they operate in the shadows, often contravening the orders of their polished counterparts at Regent’s Park. As they work to defend the nation from sinister forces, the lines between ally and enemy blur, forcing each agent to confront their past mistakes and fight for redemption in a world built on smoke and mirrors.

Slow Horses Season 5 Entire cast lineup

1- Gary Oldman as Jackson Lamb

Gary Oldman, born March 21, 1958, in London, is an Academy Award-winning actor renowned for his chameleonic versatility and powerful performances. His legendary film career includes iconic roles such as Sid Vicious in Sid and Nancy (1986), Dracula in Bram Stoker’s Dracula (1992), Sirius Black in the Harry Potter series, and George Smiley in Tinker Tailor Soldier Spy (2011), which earned him an Oscar nomination. He won the Academy Award for Best Actor for his transformative portrayal of Winston Churchill in Darkest Hour (2017). As Jackson Lamb, Oldman delivers a masterclass in character acting, embodying the slovenly, offensive, yet razor-sharp intelligence of the Slough House chief with unparalleled brilliance.

2- Jack Lowden as River Cartwright

Scottish actor Jack Lowden, born June 2, 1990, in Chelmsford, Essex, has quickly become one of the UK’s most respected talents. He first gained significant attention for his stage work, winning a Laurence Olivier Award for Best Actor in a Supporting Role for Ghosts in 2014. His breakout screen roles include a BAFTA Scotland award-winning performance in the film Calibre (2018) and pivotal parts in Christopher Nolan’s Dunkirk (2017) and the TV adaptation of War & Peace (2016). Lowden brings a compelling mix of arrogant entitlement and deeply ingrained decency to River Cartwright, the disgraced prodigy desperately seeking to restore his family’s name.

3- Kristin Scott Thomas as Diana Taverner

Dame Kristin Scott Thomas, born May 24, 1960 in Redruth, Cornwall, is an iconic actress known for her commanding presence in both British and French cinema. She rose to international fame for her role in Four Weddings and a Funeral (1994) and delivered an unforgettable performance in The English Patient (1996), which earned her an Academy Award nomination. Other notable films include Gosford Park (2001) and I’ve Loved You So Long (2008). As Diana “Lady Di” Taverner, the ruthlessly ambitious Deputy Director General of MI5, Scott Thomas is the epitome of cool, calculating power, constantly engaging in a game of chess with Jackson Lamb and the political establishment.

4- Rosalind Eleazar as Louisa Guy

Rosalind Eleazar, born in London, is a talented actress with a strong background in both theatre and television. She garnered critical praise for her role in the BBC mini-series The Pale Horse (2020) and delivered a powerful performance in the film How to Build a Girl (2019). She also starred alongside Dev Patel in David Lowery’s The Green Knight (2021). In “Slow Horses,” Eleazar portrays Louisa Guy, a capable and resilient agent whose time in Slough House has hardened her, yet who remains one of the most emotionally intelligent and dependable members of the team.

5- Saskia Reeves as Catherine Standish

Saskia Reeves, born August 16, 1961, in London, is a seasoned actress with a prolific career on stage and screen. Her notable television credits include the BBC drama Wolf Hall (2015) and the ITV series The Darling Buds of May. On film, she has appeared in Close My Eyes (1991) and The Mother (2003). Reeves plays Catherine Standish, Jackson Lamb’s former assistant and a recovering alcoholic. Her performance brings a gentle, weary, but incredibly perceptive and steadfast presence to the chaotic world of Slough House, serving as a moral compass and a source of quiet strength.

6- Christopher Chung as Roddy Ho

Christopher Chung portrays Roddy Ho, the hilariously narcissistic tech genius of Slough House. Ho lives in a delusional world where he sees himself as a suave, master hacker, completely oblivious to how his colleagues perceive him. Chung brilliantly mines the comedy from the character’s lack of self-awareness, providing much of the show’s levity, while also showcasing his genuine, albeit socially awkward, technical skills that are often crucial to the team’s success.

7- Aimee-Ffion Edwards as Shirley Dander

Welsh actress Aimee-Ffion Edwards, born November 25, 1987, is known for her roles in the TV series Peaky Blinders as Esme Shelby and in Detectorists. She brings a fierce, unpredictable energy to Shirley Dander, a former undercover agent with a ferocious temper and a history of substance abuse. Edwards perfectly captures Dander’s volatility and pent-up aggression, making her a wildcard whose explosive capabilities are both a liability and a potent asset in the field.

Supporting Cast:

The series is bolstered by an exceptional supporting cast. Irish actress Ruth Bradley (Humans, Primeval) joins as the enigmatic and capable Emma Flyte. Bally Gill (The Devil’s Hour, Trying) appears as the new, eager Agent Singh. James Callis (Gaius Baltar in Battlestar Galactica) returns as the often-outmaneuvered former MI5 chief, Claude Whelan. Samuel West (Notting Hill, Hyde Park on Hudson) is brilliantly slimy as the manipulative former Prime Minister, Peter Judd. Finally, Tom Brooke (Preacher, Bodyguard) plays the traumatized and quietly intense listening operative, JK Coe, whose skills of observation are vital.