Slow Horses Season 6 Review: Slough House Returns To Form With A Spectacular New Entry For The Popular Spy Drama

Published Sep 12, 2026, 11:37 AM EDT

Ben is a Senior Writer on the New TV team at Screen Rant. He graduated from the University of Central Lancashire with a First Class B.A. Degree in English Literature and History.

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Slow Horses season 6 delivers some of the most compelling drama and exciting subversions from the series to date, as the Slough House team returns in their most perilous mission to date. Between the return of some fan-favorite characters such as Sid Baker, played by the extraordinary Olivia Cooke, and the threat of Slough House being erased from MI5 records, this season brings back the electric intensity that launched the series in the first place.

Following the explosive conclusion of Slow Horses season 5, when Claude Whelan is compelled to resign as First Desk, this season picks up as Diana Taverner settles into her new role and the overwhelming weight of that title as she struggles to fulfill her role and maintain integrity in the face of conflicting objectives.

And as usual, while Taverner tends to dismiss the Slough House crew as being a lesser division of the agency, these are the very agents who manage to extract the truth of the situation, face down impossible odds, and keep things moving along. This season is a spectacular triumph that leaves audiences on the edge of their seat at the end of each episode, and indeed the unforgettable season finale.

Slow Horses Season 6 Is A Return To Form In More Ways Than One

While Slow Horses has never descended to the depths of other shows exceeding five seasons, the rating for the show has been on the decline for several years now. After a strong debut, with the premiere season earning Slow Horses a Rotten Tomatoes critics rating of 95% and a further 88% among audiences, the show actually managed to exceed those figures in season 2.

Slow Horses Rotten Tomatoes Scores	Critics	Audience
Season 1	95%	88%
Season 2	100%	90%
Season 3	98%	89%
Season 4	100%	89%
Season 5	96%	82%
Season 6	100%	N/A

Unfortunately, since season 2, the series has consistently gone down in the eyes of the audience, with sporadic yet extremely strong reviews from critics. With all of that in mind, Slow Horses season 6 feels like a major step up as the story takes a sharp uptick in terms of pacing and delivers the tense drama that makes this the best spy drama on TV.

It also reintroduces familiar characters like Sid Baker (Olivia Cooke), in a way that works perfectly inside the narrative, and sees everyone in the cast deliver some of their best work on the series to date. In many ways, season 6 fixes some of the issues that began appearing in previous outings, and part of that could be down to the change from one showrunner to the next.

Slow Horses Season 6 Maintains Momentum After A Major Change Behind The Scenes

Credit: MovieStillsDB

Will Smith, the British writer and producer behind the first five seasons of Slow Horses, exited the show in his showrunner capacity at the end of season 5, handing the reins over to Gaby Chiappe, and with that notable dynamic shift, there was a strong possibility that season 6 would lose the momentum established over the previous seasons.

Well, I am very pleased to report that there is no such issue, and the fact is that the opposite appears to have happened as season 6 combines two narratives from the Mike Herron novels that the series is based on for the first time, and does so with incredible elegance. There's no hint that this story has been Frankenstein-ed together, as the elements all blend together to create an unbroken and complete narrative that keeps upping the ante.

This is also a major credit to the talent in front of the camera, as they adjust to a new showrunner and attempt to bring these beloved characters back, while also being willing to adapt and change in accordance with the showrunner's vision. Ultimately, the change has only been for the better, with the result being an outstanding season of Slow Horses that pays off previous entries and pushes the narrative forward.

I Haven't Been This Excited For The Next Season Of A Show In Years

The culmination of all this, of course, comes through the entire six-episode run of season 6, but I'd be lying if I said the season cliffhanger didn't have me absolutely locked in and ready for the next season. Slow Horses has been pretty consistent with delivering compelling cliffhangers, with each season offering a trailer for what is to come in the following season.

Unfortunately, there was no such trailer at the end of the screeners, though season 7 has been confirmed to have wrapped filming, as has been the tradition for the last handful of seasons. Anyway, Slow Horses season 6 has breathed new life into the series years after it first landed on Apple TV, with twists, turns, and emotional gut punches throughout.

Slow Horses is in the strongest position it has been, potentially since the series began, and there is no sign of slowing down.

The Slough House team is in genuine peril, and that tension fills the air in every scene, contributing to a sense that every moment matters, and the only dip in the season comes at the very start, as the stage is set for the rest of the season. From episode 2 onward, hold your breath, because the story takes hold and does not let up.

The dynamics between Diana Taverner and Jackson Lamb, Sid Baker and River Cartwright, and the usual MI5 drama play out spectacularly, with stellar performances, effective twists, and a conclusion that promises the next chapter will continue to keep the audience guessing. Slow Horses is in the strongest position it has been, potentially since the series began, and there is no sign of slowing down.

Slow Horses season 6, episode 1 will be available to stream on Apple TV from Wednesday, September 16, with subsequent episodes releasing weekly.