Apple TV+’s ‘Slow Horses’ is one of the most highly rated spy thrillers of the last decade. Here’s what to know about season 5.

• “Slow Horses” is about a group of hapless spies working for MI5 in London.
• The team is led by the slobbish Jackson Lamb, played by Gary Oldman.
• The Apple TV+ series is returning for a fifth season this year.

Apple TV+’s “Slow Horses” is a gripping spy thriller about a group of MI5 agents who are relegated to administrative roles in an office called Slough House as punishment for failing a mission.

The Slough House team is led by the slobbish Jackson Lamb (Gary Oldman) who, despite his unkempt appearance, is smart enough to navigate some of the biggest threats facing the UK. Much of the series follows River Cartwright (Jack Lowden) an agent whose grandfather was a high-ranking official in MI5.

The show has a 98% score on Rotten Tomatoes, beating other recent TV espionage shows like “The Agency,” “Citadel,” and “The Day of the Jackal.”

Here’s what to know about “Slow Horses” season five.

‘Slow Horses’ season five adapts Mick Herron’s fifth book: ‘London Rules’

In January 2024, Apple confirmed that “Slow Horses” season five would adapt “London Rules,” the fifth of author Mick Herron’s “Slough House” books, which the show is based on.

Season four revealed that Cartwright’s absent father is Frank Harkness (Hugo Weaving), a ruthless mercenary who runs a network of assassins. In the last episode, Cartwright and MI5 managed to detain Harkness, arresting him for numerous assassinations and bombings.

But the show left that storyline open as Harkness appears to blackmail his way into being released by MI5.

“In season five of ‘Slow Horses,’ everyone is suspicious when resident tech nerd Roddy Ho has a glamorous new girlfriend, but when a series of increasingly bizarre events occur across the city, it falls to the Slow Horses to work out how everything is connected. After all, Lamb knows that in the world of espionage, ‘London Rules’ should always apply,” the synopsis for season five reads.

The first teaser for the season shows an unknown person shooting at Roddy Ho (Christopher Chung) and Lamb, with MI5 agent Emma Flyte (Ruth Bradley), explaining that a mysterious group is trying to “destabilize” London.

The main cast will reprise their roles in ‘Slow Horses’ season five when it returns this year

Apple has not confirmed a release date for season five, but the show is expected to come out this year. Previous seasons have debuted less than a year after the previous one, and season four premiered in September 2024. If the show keeps the same cadence, season five could arrive in August 2025, but that is unconfirmed.

What we do know is that the main cast will reprise their roles, so expect to see Oldman and Lowden as Lamb and Cartwright alongside Chung as Ho, Bradley as Flyte, Rosalind Eleazar as Louisa Guy, Kristin Scott Thomas as Diana Taverna, and James Callis as Claude Whelan.