‘Slow Horses’ Review: Fourth Season Of Apple TV+ Thriller Deepens Legacy Of Hit Show

Apple TV+’s “Slow Horses” was a surprising smash at this year’s Emmy nominations, landing nods for Outstanding Drama Series, Outstanding Lead Actor in a Drama Series (Gary Oldman), Outstanding Supporting Actor in a Drama Series (Jack Lowden), and a remarkable six other categories, including writing, directing, and editing. A program that had largely slid under the radar with its first two installments was now publicly recognized as one of the best on all television. This shift is likely to bring more viewers than ever to September’s fourth installment. The good news is that there has been absolutely no discernible dip in quality. If anything, the actors seem more comfortable than ever in these roles, and the writing this year is not only tightly constructed but deepens the themes of the best spy show on TV.

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If you’re new to “Slow Horses,” the title is a play on the British location known as Slough House, the place where MI5 agents who have faltered in the line of duty – or just earned the ire of the wrong superior – have been cast away. The leader of this island of misfit toys is Jackson Lamb (Oldman), a man who openly derides his position on the espionage ladder, but secretly loves his rebellious agents, especially River Cartwright (Lowden), once the agency’s golden child but now the best of Slough House. In a job that can be lethally dangerous, the members of Slough House have shifted over the years, but the fourth season opens with Louisa (Rosalind Eleazar), Ho (Christopher Chung), Shirley (Aimee-Ffion Edwards), and Marcus (Kadiff Kirwan) still on the job. New members this year include the mysterious J.K. Coe (Tom Brooke) and the administratively minded Moira (Joanna Scanlan).

Jackson’s team of lovable losers are often offset against the seemingly superior but often morally compromised agents of MI5, led by Diana Taverner (Kristin Scott Thomas). It’s joyous whenever Thomas and Oldman get to battle wits in a scene together, both resigned to the roles they play in the world of espionage but almost unable to do anything else. Thomas is particularly great this season, butting heads with another idiot in a suit at First Desk named Claude Whelan, played perfectly by James Callis, who gets the kind of guy who takes credit for other people’s success and passes the buck on his own failures.

Whelan is distinctly unqualified to handle the situation when a suicide bomber drives into a crowded mall and commits mass murder. Agent Emma Flyte’s (Ruth Bradley) investigation into the explosion leads her to a connection to David Cartwright (Jonathan Pryce), River’s grandfather, who is sadly battling the deterioration of dementia. After a shocking act of violence in David’s house in the premiere, the season of “Slow Horses” tracks a character that won’t be spoiled to France, hunting down the connection between the Cartwright family and what appears to be a group of assassins closing a few loose ends from the past. The great Hugo Weaving leads this crew as Frank Harkness, and his connection to the Cartwrights is one that viewers won’t see coming, but that, without spoiling again, fits the theme of this season and really the show overall.

“Slow Horses” is about a group of people who have often allowed their ethical cores and personal connections to allow them to be deemed inadequate in the eyes of MI5. Of course, having a heart helps in the spy game too, and each season has really been about how what is often considered weak in the eyes of espionage is not a flaw but an asset. The growing connection between River and Jackson is tested in the fourth season of “Slow Horses” in ways that are unpredictable, but incredibly narratively rewarding too. It helps that the writers of “Slow Horses” are deft at staying one step ahead of their viewers in a manner that makes this show one of the quickest watches on television. While so many programs sag not only mid-season but mid-episode, “Slow Horses” makes the most of its 6-episode structure, packing just enough twists, turns, and character detail into each chapter.

Of course, it’s no surprise that Weaving fits into this world perfectly, but it’s the regular cast that really shines this season. Thomas has slowly turned up the dial on Taverner’s world weariness with each season in manner that’s captivating, making her an even better balance for Oldman’s Lamb in that they’re both just exhausted with the incompetence they see around them, but know that it would only get worse if they left. A show like this work better the more the performers and writers lean into their characters, and now that 24 episodes have unfolded, it’s virtually impossible to imagine anyone else in the main roles here.

If there’s a flaw in this adaptation of “Spook Street” – each season is based on a different book by author Mick Herron with the fifth in production adapting “London Rules” – it might be that it goes by almost too quickly. There’s so much plot and character in the fourth chapter of “Slow Horses” that it’s almost difficult to keep up with what’s happening, but that’s partially by design. It’s a season clearly meant to reflect not just the confusion of David Cartwright’s shaky memory, but the sense that all of the power structures in this world are built on foundations of buried secrets that are always threatening to tumble out. It’s rarely been more entertaining to watch them fall. [A-]

“Slow Horses” Season 4 debuts on Apple TV+ on September 4.