There’s something delightfully perverse about Slow Horses, that with its fourth season, continues to be one of television’s sharpest spy dramas. As a show about MI5’s discarded agents, who have been banished to the drab purgatory of Slough House, it offers the pleasure of watching world-class incompetence in action. Yet, for all its focus on its bumbling misfits, Slow Horses has proven itself anything but. Where the slick gadgets and flashy car chases have saturated the genre to death, the series keeps it simple: a masterclass in how to spin pure gold from the rustiest of parts.

The sneering cynicism of the Apple original, which continues to build on the show’s cult following, lies in its refusal to take itself too seriously, no matter the stakes. The show is, after all, led by Gary Oldman’s Jackson Lamb, the unapologetically crass, unkempt head of Slough House, whose brilliance hides beneath a greasy veneer of disdain and sweat. Lamb remains as vile and flatulent as ever, and looks as though he hasn’t bathed in four seasons. Oldman turns in yet another spectacular performance, weaponising his slovenliness to keep everyone around him off balance. His insults are just as acidic as ever, landing with a kind of pungent authority and layers of grease-stained derision. 

And yet, you can’t help but admire him — Lamb is the anti-Bond we didn’t know we needed. The man may appear to be decomposing before our very eyes, but his mind remains as sharp as ever. It’s a performance that should have grown stale by now, but instead feels invigorated, as if Oldman, like the show itself, has found new layers of grime to explore. But Slow Horses isn’t merely the Lamb show; it is an ensemble piece, and the motley crew of Slough House agents are just as compellingly pathetic as ever. 

Jack Lowden’s River Cartwright — who has been chasing his redemption arc for what feels like an eternity — gets drawn into a plot that revolves around his ailing grandfather, former MI5 legend David Cartwright (the inimitable Jonathan Pryce). River’s one-man mission to solve a mystery involving a terrorist bombing that dredges up explosive secrets from the past, is at the heart of this season, though whether River is a hero-in-waiting or simply a glutton for punishment still remains unsurprisingly uncontested in spite of its revelations. 

Meanwhile, Rosalind Eleazar’s Louisa and Saskia Reeves’ Standish take a bit of a back seat this season, as Kadiff Kirwan’s Marcus and Aimee-Ffion Edwards provide occasional glimpses of competence, while Christopher Chung’s Roddy Ho, remains as obnoxiously insufferable as ever. 

It’s this interplay of bumbling yet oddly capable outcasts that makes the series feel alive, as if even in the most absurd situations, the characters are acutely aware of the ridiculousness of their own predicament. Watching them make their way through the chaos serves to remind us  that in Slow Horses, it’s not about winning, rather surviving the season with as little dignity as possible (you can’t have both).

Newcomer James Callis is delightful to watch as Whelan, the slippery new First Desk whose nervous half-confidence is as entertaining as it is dangerous. Meanwhile, Ruth Bradley’s new top Dog, Flyte, is an interesting outsider’s perspective to the fresh hell that is Slough House and its exasperating antics.

Hugo Weaving steps in as a sinister new villain, poised to make full use of yet another skeleton from MI5’s ever-expanding closet of sins. While his predictable tie to River might raise an eyebrow, his grand scheme — raising an emotionless death squad in a hauntingly picturesque French mansion, complete with amnesia and murmurs of a “monster”— feels like a page ripped out of Naoki Urasawa’s influential manga/anime, Monster.

The plotting of Season 4, adapted from Herron’s fourth novel Spook Street, may not offer anything radically new, but what it does, it does rather well. The arc moves with precision, never letting the pace flag. Even when the action settles into quieter, more contemplative moments, like Pryce’s David grappling with his own slipping mind, the stakes still feel high. 

The series continues to thrive on the grimy aesthetics that make it feel so unique. Where other spy dramas relish the glow of exotic locales, Slow Horses luxuriates in the withering corridors of Slough House and the rain-soaked gloom of London. There’s something almost comforting in how utterly unglamorous it all is. The show’s London is one where spies drink tepid pints and stumble down alleys, rather than slink through nightclubs in tailored suits. And yet, in all its downtrodden glory, Slow Horses remains a thing of beauty. It’s hard to look away from a series that feels so lived-in, so utterly convinced of its own grimy brilliance.

As the wheels of espionage continue to turn, dragging our beleaguered agents through the muck of MI5’s dirty secrets, there’s an undeniable thrill in watching horses trod along toward disaster — and somehow, against all odds, come out the other side. With a fifth season on the horizon, one thing’s clear: these slow horses are going nowhere fast, and that’s exactly why we love them.

All episodes of Slow Horses Season 4 are currently streaming on Apple TV+