‘Slow Horses – Season 6’ Apple TV Review: Still the Best Spy Show on Television

One of the finest and most consistently excellent shows in the streaming landscape, Slow Horses arrives at its sixth season operating like a perfectly drilled machine —a championship-caliber team in which everyone knows exactly what they’re supposed to do and executes flawlessly. The stories click, the tone is almost always pitch-perfect, the characters remain exceptional, and across six lean episodes there’s barely a wasted moment. Once again, the series proves itself a cut above virtually everything else in the spy genre. At this point, it’s impossible to deny: Slow Horses has become a television classic.

At the center of that well-oiled machine is, unquestionably, Gary Oldman, the show’s darkly hilarious beating heart. His Jackson Lamb is one of television’s all-time great creations, and by now it deserves to be mentioned among the finest performances of Oldman’s extraordinary career. That’s saying something for an actor who has spent more than four decades building an unforgettable gallery of characters ever since his breakout as Sid Vicious in Sid & Nancy (1986). Despite the greasy hair, appalling diet, cutting insults, foul smell, and permanently disheveled appearance, Lamb remains an exceptionally sharp, pragmatic, and fiercely loyal leader to his band of «slow horses»—the disgraced MI5 agents relegated to Slough House.

This season adapts not one but two Mick Herron novels —Joe Country and Slough House— and centers on a mystery involving someone systematically hunting down members of Slough House. To make matters worse, their records have mysteriously vanished from MI5’s files. The assassins aren’t just targeting current agents; they’re going after retired operatives as well, eliminating them with chilling efficiency. Lamb and his team must track down former colleagues before the killers do, keep them hidden while staying off the grid themselves, and figure out who’s behind the operation and why. Unsurprisingly, the answers involve Russian operatives, far-right media organizations, long-buried secrets, and the ever-complicated interference of MI5 itself, with Diane Taverner (Kristin Scott Thomas) once again pursuing objectives that often clash with Lamb’s.

As always, the show’s emotional anchor is River Cartwright (Jack Lowden), who—Season 5 spoilers ahead—is still grappling with the death of his grandfather David (Jonathan Pryce). His story this year revolves around several unexpected figures from his past re-entering his life, some welcome and others decidedly less so. Their return not only disrupts River’s personal journey but also ties directly into the season’s central conspiracy. When Slow Horses focuses on River, it occasionally slips into more familiar spy-thriller territory, but that subplot provides exactly the emotional and narrative balance the series needs. It grounds the increasingly outrageous antics of Jackson Lamb without ever sacrificing the emotional stakes.

That delicate tonal balancing act —a series whose characters rarely seem to take themselves seriously even though the show itself absolutely does— is what continues to separate Slow Horses from its contemporaries and, increasingly, from the many shows that have tried to imitate it. Created by Will Smith and once again directed this season by Adam Randall, the series effortlessly blends razor-sharp dialogue, dry wit, biting irony, genuine suspense, and real emotional commitment. Herron and company are never afraid to kill off major characters or put them through devastating physical and psychological ordeals. In fact, this season’s finale may well be the bleakest and most brutally violent episode the series has produced.

The other key ingredient in Slow Horses‘ enduring excellence is its discipline. Six episodes, each running around 45 minutes, fly by without ever feeling rushed. Just as importantly, Apple has turned the show into an annual event, delivering a new season every year. That regular rhythm means viewers never have to spend half a season remembering who everyone is or how the previous story ended. Lamb is back. His dysfunctional B-Team is back —including the endlessly patient Catherine (Saskia Reeves) and the gloriously insufferable Roddy (Christopher Chung). Reuniting with them each year increasingly feels like catching up with the dysfunctional family you swear you can’t stand but secretly love. And somehow, with every season, you love them a little more.