TV-MA | 6 episodes | Thriller | 2026

If you had a boss who was as acerbic and cantankerous as Jackson Lamb (Gary Oldman), you would probably quit. Will Smith’s hit series, “Slow Horses,” is compulsively watchable and more positive than you'd think. The series, based on Mick Herron’s novels, releases its drolly written sixth season on Apple TV+.

Frankly, MI5, the UK’s domestic counterintelligence agency, would not mind if Lamb’s agents resigned. It would save them a lot of trouble. Lamb oversees Slough House, where agents, called Slow Horses, get transferred after committing very public mistakes.

For various reasons, agents assigned to Slough House cannot be fired, but their careers effectively end under Lamb’s dismissive management style. Nevertheless, the cast-off agents regularly discover and thwart serious threats to national security.

In Season 6, “Jim and Jane” (Kyle Soller and MyAnna Buring), a mysterious pair of assassins, have been working their way through a kill list of former Slow Horses.

Alarming Deaths

To add further insult, MI5 has stopped paying Slough House agents because their files have been nefariously wiped from the system. Although Lamb shares MI5’s low estimation of the deceased, his suspicious mind identifies an alarming pattern.

Of course, his equally sarcastic colleague Diana Taverner (Kristin Scott Thomas), the Deputy Director General of MI5, brushes off his concerns, but that, in a way, further fuels his suspicions.

As deaths among the Slow Horses increase, Lamb orders the survivors to regroup in an off-the-books safehouse while he pursues a potentially relevant witness.

Afflicted with Spranger-Weidemann disease (a form of dwarfism), young, foul-mouthed Reece Nesmith (Lenny Rush) secretly watched Frank Harkness (Hugo Weaving) murder his ex-MI5 father, Andy (Dylan Smith), to cover up the former agent’s role in stealing the Slow Horses list.

River Cartwright (Jack Lowden) is having an even worse day than his colleagues. He still grieves a recently deceased grandfather, David (Jonathan Pryce, who appeared in prior seasons). Cartwright barely survives an encounter with his disgraced assassin father, the very same Harkness, at the funeral.

Cartwright soon discovers that former Slow Horse Sid Baker (Olivia Cooke), who was presumed dead during Season 1, is in fact alive, though not necessarily well. Jim and Jane have targeted her as the next victim on their list, which also includes Cartwright.

Mordantly Funny

“Slow Horses” is probably the most mordantly funny spy series on streaming television. That is also why it has built such an enthusiastic following. Of course, the inspired casting of Oldman and Thomas as the bickering MI5 spy-masters perfectly suits the series’ snarky tone, and keeps it unusually faithful to the spirit of Herron’s books.

Listening to Lamb and Taverner trade dryly mocking barbs is even more entertaining than each episode’s helpings of action and intrigue (which are also cleverly conceived).

As a considerable bonus, Season 6 boasts an almost equally cynical nemesis, in the person of Weaving’s Frank Harkness. He returns from Season 4 and might even be crustier and crankier than Lamb.

His torturous relationship with his beleaguered, straitlaced son, Cartwright, adds further layers of irony to the murky conspiracy afoot. Likewise, the BAFTA-winning Rush fits right in with the series’ razor-sharp dialogue and caustic attitude. As was true for the past five seasons, poor Lowden looks the part of a square-jawed action hero playing Cartwright, but his more colorful costars constantly overshadow him.

For serious espionage enthusiasts, the series opens a fascinating window into the inner workings of MI5. John le Carré has long been considered an influence on Herron’s books, and Jackson Lamb (initials “JL”) has been presumed to be an homage to the “Smiley’s People” author.

While viewers need little advance knowledge to appreciate the show’s sardonic charms, fans of the genre will appreciate the cunningness of the Russian FSB’s behind-the-scenes string-pulling and the crafty ways that Lamb navigates the chaos.

Signature Role

Lamb could very well become Oldman’s signature role. After six seasons (with at least one more on the way), fans can’t imagine anyone else portraying Lamb.

Thanks to Oldman, “Slow Horses” is still far and away the most rumpled spy thriller on any streaming platform. It is darkly twisty in endlessly amusing ways.

The original theme song, “Strange Game,” performed and cowritten by Sir Mick Jagger, aptly captures the vibe of Slough House when he sings “surrounded by losers, misfits and boozers, you’re finished, you’re foolish, you failed.”

Yet somehow, viewers can’t help rooting for this motley crew of mess-ups. Indeed, each largely stand-alone season is weirdly redemptive. Season 6 maintains the quality of previous story arcs.

Highly recommended for fans of witty espionage thrillers.

“Slow Horses” Season 6 streams on Apple TV+ Sept. 16.

‘Slow Horses’ Season 6
Director: Adam Randall
Starring: Gary Oldman, Kristin Scott Thomas, Hugo Weaving, Jack Lowden, Olivia Cooke
Rating: TV-MA
Running Time: 6 episodes (approx. 50 minutes each)
Release Date: Sept. 16, 2026
Rated: 4 stars out of 5

What arts and culture topics would you like us to cover? Please email ideas or feedback to features@epochtimes.nyc.