The trailer video for the fourth season of Slow Horses was released by Apple TV+ on Tuesday.

The glimpse shows that this season opens with a bombing, unveiling some personal secrets and shaking the already unstable foundations of Slough House. It will be a double-whammy situation for River Cartwright (Jack Lowden), as he has to deal with his grandfather's deteriorating mental health and the aftermath of the bomb blast.

The series, which recently got renewed for the fifth season, is a British spy thriller based on the Slough House novels by Mick Herron. The series follows British MI5 agents who work together in a dumping ground called Slough House after committing mistakes that ended their careers.

This particular season will be an adaptation of Herron's 2017 novel, Spook Street.

The main cast will return, including Gary Oldman as Jackson Lamb, Jack Lowden as River Cartwright, and Kristin Scott Thomas as Diana Taverne. The new cast members include Hugo Weaving as Frank Harkness, Ruth Bradley as Emma Flyte, James Callis as Claude Whelan, Joanna Scanlan as Moira Tregorian, and Tom Brooke as JK Coe.

Slow Horses is backed by See-Saw Films and adapted for television by Will Smith. Jamie Laurenson, Hakan Kousetta, Iain Canning, Emile Sherman, Douglas Urbanski, Gail Mutrux, Will Smith, Jane Robertson and Graham Yost serve as executive producers on the series.

The first two episodes of Season 4 will debut on Apple TV+ on September 4, 2024, with the remaining four episodes released weekly until the finale on October 2, 2024.