Slow Horses books: How to read the Jackson Lamb novels in order

Now that it's September, like clockwork, acclaimed spy series Slow Horses is back for a new season on Apple TV.

This sixth run is based on two of Mick Herron's novels, Joe Country and Slough House, and sees the Slow Horses going on the run when Diana Taverner embroils them in a dangerous game.

Explaining the decision to merge the plots of two novels, director Adam Randall recently told Radio Times: "I read Joe Country and Slough House. They're both fantastic. Joe Country would make the most amazing film, but it was felt that there was not a huge amount of story for a number of our characters.

"Taverner’s not in it a great deal, Lamb hasn't got a huge amount to do, so it was sort of the decision to combine them and find a way for them to work together. But then we had the opportunity to draw on both of them throughout the process, which was really fortunate."

The new season once again stars Gary Oldman, Jack Lowden and Kristin Scott Thomas, and arrives a year after Herron's latest novel in the series, Clown Town was released – it seems it's still full steam ahead for both Herron and for Apple's adaptation of his works.

Read on for everything you need to know about how to read the Jackson Lamb novels in order.

Is Slow Horses based on a book?

Yes – the television series is based on the Slough House series, a long-running collection of books featuring the brilliant but irascible Jackson Lamb, who's played on screen by Gary Oldman.

The first season of Slow Horses was based on the first book in the series, while the second season was based on the follow-up book, Dead Lions. Season 3, likewise, was based on the third book in the series, Real Tigers, with season 4 being based on the fourth book, Spook Street, and season 5 being based on the fifth book, London Rules.

Season 6, meanwhile, has been the first to adapt two books, merging the plots of book 6, Joe Country, and book 7, Slough House.

Herron has been very supportive of the adaptation, and has had oversight of any changes made to the stories – even coming up with some of them himself.

In 2025, he told Radio Times exclusively: "For me, the biggest difference between the novels and the adaptation is purely the medium. I think that everything that could be done to bring a book onto the screen has been done by [then-showrunner Will Smith] and the other writers and the producers and designers and everybody involved.

"Obviously, there have to be changes, because most novels, and certainly mine, deal with interiority. You can't go into a character's head – I mean, not without doing voiceover. So, instead of me writing down all the characters' thoughts and feelings, we find different ways to portray them on the screen.

"But it's done with such enormous fidelity to the characters – not to the plots, which is not important to me, but to the characters, which is important to me – that the difference is purely one of transmission. [Smith] totally, as do the other writers, gets the mood and tone of the books."

How many books are there in the Slough House series?

There are currently eight books in the Slough House series, with the most recent being released on 11th September 2025.

Here's the full list of Slough House novels in order.

1. Slow Horses (2010)
2. Dead Lions (2013)
3. Real Tigers (2016)
4. Spook Street (2017)
5. London Rules (2018)
6. Joe Country (2019)
7. Slough House (2021)
8. Bad Actors (2022)
9. Clown Town (2025)

Alongside the nine novels, Herron has also written four novellas in the series - The List (2015), The Marylebone Drop (2018), The Catch (2020) and Standing by the Wall (2022).

Meanwhile, Herron's novels Reconstruction (2008), Nobody Walks (2015) and The Secret Hours (2023), while not officially part of the series, take place in the same world and include some of the same characters.

We don't yet know if Slow Horses’ success will see these spin-off books also brought to screen. "There haven’t been discussions about filming them, but it certainly remains a possibility," said Herron back in 2022. "For the time being, it's the Jackson Lamb series which is being focused upon."

Former showrunner Will Smith then called The Secret Hours "a wonderful book", and said "there's definitely an opportunity to do a shorter-run [series] or a film or something".

Meanwhile, Tom Brooke, who plays JK Coe, has said he would be "game" for a spin-off telling the story of Nobody Walks, which includes his character's backstory.

Most recently, Smith, who left the show following the fifth season, has said that he could see himself returning to adapt The Secret Hours, adding that it's "the one I was always saying we should do" as a spin-off.

"He started writing a standalone book in the Slough House universe, and you could feel the Slow Horses coming in, and it ends up flashing back to it," Smith said of Herron. "It’s a kind of Lamb/Molly/David prequel, as well as a book set in the present.

"And it’s absolutely brilliant. And it’s one of my favourites he’s done. I think that could be a great standalone film or a three-episode miniseries."

Does Jackson Lamb feature in all of the novels?

Lamb appears in all of the Slough House novels, meaning there should be plenty of scope for Gary Oldman to return as the character time and again. However, in an exclusive interview with Radio Times, Oldman revealed that Herron hadn't always intended it to be that way.

Oldman explained: "Lamb was never originally going to appear. Lamb was up somewhere on the eighth floor, or the seventh floor or somewhere in the building and that he was such a sort of legend that people talked about him, but he never appeared.

"And Mick said that he wrote one scene with Lamb and once he gave him the voice, he went, 'Oh no, this guy's too interesting,' and that's how the whole thing shifted – which is fascinating to me that he was going to be an off-stage character."

Will the Apple TV series adapt more of the books?

It will indeed. Filming has already taken place on a seventh season of the show, which will adapt 2022's Bad Actors.

Meanwhile, an eighth season has also been confirmed, with that run set to be based on 2025 novel Clown Town. At that point all of the mainline series thus far will have been adapted, and it is not clear where the show will go from there.

If it is to continue, the series may either have to make up new plots, or wait for Herron to continue his book series.

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Herron previously told Radio Times that he’d be "delighted" if his whole run of novels did get adapted.

He said at the time: "I'd be delighted if that does happen – everybody seems to be happy with the work done so far, but we've no way of knowing what the future holds."

Slow Horses is available to stream on Apple TV. Season 6 is being released weekly, with new episodes arriving on Wednesdays. Start your seven day free Apple TV trial.

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