Apple TV's Slow Horses has quietly become one of the most reliable thrillers on streaming, and the new Season 6 trailer promises the most dangerous chapter yet for the disgraced MI5 agents of Slough House. The series, starring Academy Award winner Gary Oldman, returns next month with a fresh batch of episodes that adapt the sixth and seventh books in Mick Herron's acclaimed Slough House novels.
The trailer opens with Jackson Lamb doing what he does best—showing up uninvited. He sneaks into Diana Taverner's (Kristin Scott Thomas) home at night, settles into her garden, and gives a cheeky wave to get her attention. Their conversation quickly turns tense as Lamb demands to know why his agents keep dying. Taverner insists she hasn't angered anyone enough to have former members burned alive in shipping containers, but the remaining Slow Horses aren't convinced. They start coordinating to protect each other, even if they're terrible at following Lamb's advice to "go dark."
All signs point to River Cartwright (Jack Lowden) as the next target, setting off a high-octane chase that could finally do him in. The trailer keeps the show's signature blend of dark comedy and high-stakes espionage, with plenty of witty banter and explosive action. It's a tone that has made Slow Horses a standout in the spy genre, and it shows no signs of slowing down.
A Fan-Favorite Returns
One of the biggest surprises in the trailer is the return of River's biological father, played by Hugo Weaving. River doesn't trust his dad's "business" as far as he can throw him, but he might be the least of the spy's worries. The rest of the ensemble is back, including Christopher Chung, Aimee-Ffion Edwards, Rosalind Eleazar, Joanna Scanlan, Samuel West, Ruth Bradley, Tom Brooke, and Jonathan Pryce. Newcomer Lenny Rush joins the cast, and Olivia Cooke reprises her role as Sidonie "Sid" Baker for the first time since her character was shot in the head in Season 1.
Season 6 finds MI5 under new leadership with Taverner as First Desk, but her promotion doesn't bring peace. Instead, the Slow Horses—both current and former—find themselves in a deadly game of retaliation and revenge. The trailer suggests that no one is safe, and the body count could be higher than ever.
Slow Horses has been a critical darling since its debut, with every season earning a Certified Fresh rating on Rotten Tomatoes. It's also been a ratings juggernaut for Apple TV, which has already renewed the series for a seventh season. That renewal brings the show closer to adapting all nine novels in Herron's series, a feat that few streaming shows achieve.
Gaby Chiappe adapted Season 6 for television, with Adam Randall returning to direct. The show's success has also helped cement Apple TV's reputation for quality programming, alongside other hits like The Diplomat and other top-tier thrillers.
For fans of the genre, Slow Horses remains a must-watch, and this new season looks to be its most intense yet. If you're looking for more spy thrills, check out our list of the best thriller TV shows since 2020.
Slow Horses Season 6 premieres on Apple TV on Wednesday, September 16. Watch the full trailer above.
