'Slow Horses' season 4 release date, cast, trailers and more

If you watched the latest season of "Slow Horses," you'd know that season 4 has been confirmed. This Apple TV Plus show has been one of the best shows on TV since its first episode and season 3 was the best TV show I watched in 2023. And one of the reasons I love this show so much is that at the end of every season, the showrunners drop a trailer for the next season.

Season 3 was no different, and once episode 6 of season 3 wrapped up, we got a trailer for the upcoming season 4. There's a fair amount we already know about the new season, including that we'll see a trailer for the already greenlit season 5 after the final episode. So here's everything we know about "Slow Horses" season 4, including the show's release date, cast, trailers and more.

Despite having a trailer for season 4, we don't quite know when the next season of "Slow Horses" will arrive on Apple TV Plus. But showrunner Will Smith (no, not that Will Smith) said in an interview with Decider that the first episode will definitely arrive on the streaming service before the end of 2024.

We expect "Slow Horses" to be released on Apple TV Plus at the end of November 2024. The last season arrived on Wednesday, November 29, 2023 and the season before that arrived on Friday, December 2, 2022. If I had to guess an exact date for season 4, I'd go with Wednesday, November 27, 2024, with the first two episodes dropping on that day and the season 4 finale hitting Apple TV Plus on Wednesday, December 25.

Talk about an incredible Christmas present. Spoiler alert: Spoilers for seasons 1 4 of "Slow Horses" beyond this point Despite a now familiar ensemble cast, the show's main cast is a surprisingly small group. Gary Oldman's Jackson Lamb, Jack Lowden's River Cartwright and Kristin Scott Thomas's Diana Taverner are the only core members of the "Slow Horses" cast.

However, thanks to the new trailer and some casting announcements we can make an educated guess at who to expect in season 4. Here's the full cast we know so far: Apple has yet to drop an official trailer on YouTube, but thankfully some intrepid soul has uploaded it for us. You can watch it below, though from here on out we get into spoiler territory.

The first trailer for season 4, which we see at the end of season 3, shows Jackson Lamb in a miserable state — not that he'd tell you. Meanwhile, a bomb has exploded in London and MI5 is in shambles. Emma Flyte (Ruth Bradley), appears as a new member of MI5 and is now seemingly a liaison between Slough House and MI5.

MI5 is now led by Diana Taverner, and she's using Flyte to inquire about the state of Lamb's "rejects." And then there's River Cartwright, who unsurprisingly is now stuck in another dangerous situation opposite a menacing Frank Harkness (Hugo Weaving) who either wants River to join him or die.

As if that wasn't bad enough, he's also dealing with his grandfather's (Jonathan Pryce) deteriorating health. If this trailer for season 4 is any indication, we can expect the same wonderful blend of tension, action, wit and charm that makes "Slow Horses" so great. Season 4 of "Slow Horses" has been confirmed to be an adaptation of Mick Herron's 2017 novel "Spook Street," the fourth novel in his Slough House series.

I'm not going to go into full spoilers here — if you want to know everything that could happen, do some spy work and read the book for yourself. I will, however, give you a brief synopsis of what to expect, and that will entail some spoilers from the past three seasons as well as potential spoilers for season 4.

In season 3, we start to see Jonathan Pyrce's David Cartwright (River's grandfather) start to show concerning, early signs of dementia. Those concerns, unfortunately, are real, and in "Spook Street" River must deal with his grandfather's deteriorating mental state while also dealing with a bombing that has killed dozens of civilians.

Season 4 will certainly be messy and won't pull any punches. It'll also be the last time we see a certain cast member — at the end of the season 4 teaser trailer Gary Oldman's Jackson Lamb announces one of his team has died..