With an unapologetically raw edge, providing insight into MI5’s most troubled agents at the infamous Slough House. With the brutal directness of Jackson Lamb leading his odd crew of agents, fans are excitedly awaiting Season 6 to bring new challenges, tension, tension, tension, and classic British humour to spy drama storytelling. In the wake of the unexpected twists and emotional journey from Seasons 4/5 and building on the tension around them, they want nothing more than to see these characters continue to create stories that keep them in suspense (and glued to the screen) until Season 5 airs in 2025.
Slow Horses Season 6 Current Status
Slow Horses Season 6 is NOT coming in March 2026. As of February 2026, Apple TV+ has not announced an official release date for Season 6. While filming has already wrapped, all reliable industry sources point to a 2026 release, most likely in the fall window (September–October 2026).
Season 4 was in September–October 2024, while Season 5 was in September–October 2025. Apple TV+ has maintained a near-annual autumn release pattern for the show
Some fan speculation suggests May–June 2026 based on post-production timelines, but no credible outlet supports a March 2026 premiere. Any mentions of early 2026 relate only to teasers or first-look promos, not the full season.
Slow Horses Season 6 Expected Cast
The core cast is expected to return, led by:
- Gary Oldman as Jackson Lamb
- Jack Lowden as River Cartwright
- Kristin Scott Thomas as Diana Taverner
- Saskia Reeves, Rosalind Eleazar, Christopher Chung, and Jonathan Pryce
Season 6 continues adapting Mick Herron’s Slough House novels, meaning new guest characters are expected, though Apple TV+ has not officially announced additional casting yet.
Slow Horses Season 6 Potential Plot
The sixth chapter of the Slough House series will be called “Joe Country” and is one of most darker books in the Slough House series.
It is expected that a more personally brutal threat pertains to Jackson Lamb’s past, a shift from London-centric/urban themes of espionage to rural and political extremism themes, River Cartwright being pulled into very dangerous areas, and MI5 will see increased internal power struggles.
It is also expected that the tone will be much grimmer and more violent, as well as for both Lamb and the Slough House team to have consequences from their past actions come back to them.