Every Season Of ‘Slow Horses’ Ranked By Its Rotten Tomatoes Score

‘Slow Horses’ has quietly become one of the steadiest performers in prestige television, and its Rotten Tomatoes history proves the point. The Apple TV+ spy thriller is based on the series of Slough House novels by Mick Herron, and it premiered on April 1, 2022, to critical acclaim and huge popularity. Its ensemble cast includes some of the leading names in British acting, among them Gary Oldman, Kristin Scott Thomas, Jack Lowden, and Jonathan Pryce.

What makes the show unusual is not just its quality but its consistency. Across six installments, ‘Slow Horses’ has never dropped below a 95 percent approval rating on Rotten Tomatoes. With that kind of track record now fully on the books, here is how each season stacks up against the others.

Season 1 Opens Slough House At 95 Percent

The first season follows a dysfunctional team of MI5 agents and their obnoxious boss, the notorious Jackson Lamb, as they navigate the espionage world’s smoke and mirrors to defend England from sinister forces. The story centers on River Cartwright, a young agent banished to Slough House after a botched airport operation, whose team gets pulled into the kidnapping of a British student by a far right extremist group. The season currently holds a 95 percent Tomatometer score from 60 reviews.

Critics were quick to single out the cast even where the plotting felt familiar. Reviewers praised how the show reworked the espionage genre by making its team of operatives bumbling rather than glamorous, with Oldman’s performance drawing particular attention. It remains the lowest scored entry in the franchise, though a 95 percent debut is a benchmark most new dramas would envy.

Season 5 Settles Into Second To Last At 96 Percent

Adapting Mick Herron’s novel London Rules, the fifth season registers a 96 percent score on Rotten Tomatoes. The storyline kicks into gear when Slough House’s resident computer expert, Roddy Ho, unexpectedly acquires a glamorous new girlfriend. Elsewhere in the season, a mass shooting rocks London and intensifies a testy mayoral race, with Shirley coming to believe one of the slow horses was the actual target of an attempted hit.

Some reception described this run as slightly more divisive than its predecessors, yet it still landed comfortably within the show’s elite range. A 96 percent score, especially five seasons into a series, speaks to how rarely ‘Slow Horses’ has wobbled creatively.

Season 3 Climbs To 98 Percent

Season 3 sits at a 98 percent Tomatometer score across 44 reviews, with an 88 percent audience Popcornmeter rating. Drawn from Herron’s third novel Real Tigers, the season follows a romantic liaison in Istanbul that threatens to expose a buried MI5 secret in London, dragging Jackson Lamb and his team into a conspiracy that endangers the future of Slough House and MI5 itself. New additions to the cast for this run included Sope Dirisu and Katherine Waterston.

Critics described the season as reaching a fuller gallop, calling it possibly the most compelling operation the Slough House team had run to that point. The combination of an Istanbul set piece and rising personal stakes for Catherine Standish gave the show room to deepen its characters without slowing down the plotting.

Season 2 Reaches A Perfect 100 Percent

Season 2 has a perfect 100 percent critics score on Rotten Tomatoes, alongside a near perfect audience score. The Rotten Tomatoes critics consensus for the season noted that it avoided the usual sophomore slump, delivering a follow up that some argued surpassed its already addictive first year. The six episode season saw long buried Cold War secrets emerge that threatened to bring carnage to the streets of London.

This was the season that proved ‘Slow Horses’ was not a one off. Rather than coasting on its premise, the show tightened its plotting and its comedic timing, and the results showed up immediately in how critics responded.

Season 4 Matches The Series Best

Season 4 also debuted with a perfect 100 percent score on Rotten Tomatoes. Adapted from Herron’s Spook Street, the season opens with a bombing that detonates personal secrets, rocking the already unstable foundations of Slough House. The storyline also leaned into David Cartwright’s advancing dementia, which puts River’s grandfather in danger as old secrets resurface, and introduced Hugo Weaving as Frank Harkness.

Reviewers who screened the season early called it possibly the show’s best outing yet, with particular praise for how much more heroic Jack Lowden’s River had become. A perfect score four seasons in suggested the writers’ room had found new gears rather than running out of them.

Season 6 Sets A New Franchise Record At 100 Percent

Season 6 debuted at a perfect 100 percent on Rotten Tomatoes, a score currently based on 10 reviews. Its Average of Rated Reviews sits at 8.90 out of 10, a new series record for the Apple TV adaptation, and the season premiered on Wednesday, September 16. The new episodes adapt two of Herron’s novels, Joe Country and Slough House, rather than just one, marking a new format for the show.

The season finds the Slough House operatives on the run across Britain after becoming targets in a ruthless game of institutional retaliation, facing extreme physical peril in harsh winter terrain while dodging assassins and government pursuers, as Diana Taverner wages an uncompromising battle to hold onto her grip on power at MI5. Taken as a whole, the show’s overall series Tomatometer now stands at 98 percent. That is a remarkable number for a spy drama six seasons deep, and it caps off a ranking where the difference between the best and worst season on Rotten Tomatoes is a mere five points.

With Jackson Lamb’s crew now scattered across a snowbound Britain and Diana Taverner fighting for her career, which season of ‘Slow Horses’ do you think earned its Rotten Tomatoes score the most.