Apple TV's spy drama Slow Horses will depart from its established episodic formula when Season 6 premieres on 16 September, bringing back several characters from earlier seasons rather than opening with an entirely fresh case. Previously, each six-episode run introduced a new standalone mystery for the disgraced MI5 agents of Slough House, led by Jackson Lamb (Gary Oldman), to solve within that season. The shift towards a more serialised structure marks a notable change for a show that has built its reputation on tightly contained, resolvable storylines.

Returning characters include Louisa Guy (Rosalind Eleazar), Frank Harkness (Hugo Weaving) and, most surprisingly, Sidonie "Sid" Baker (Olivia Cooke), whose fate had been left ambiguous since she was shot in Season 1. The new season, which sees both past and present Slough House operatives targeted by an unknown group, will also be adapted from two of Mick Herron's novels rather than one, and comes with a new head writer, Gaby Chiappe, replacing outgoing showrunner Will Smith. Season 7 has already been greenlit.