‘Slow Horses’ fans in shock after deadly season six finale: “The best hour of TV this year”

Slow Horses fans have been left in shock after the devastating finale of season six that saw several characters gunned down.

READ MORE: The best TV shows of 2026… so far! Season six saw the return of Olivia Cooke’s MI5 agent Sidonie Baker after a four-year absence from the hit thriller.

The happy reunion with fellow spy River Cartwright (Jack Lowden) didn’t last long though, with the pair fleeing from Russian sleeper agents.

The final episode aired last night (Wednesday October 21) and saw MI5 employees Louisa, Standish, Moira and Shirley joining up with Roddy, Emma Flyte, Reese Nesmith and River in a safe house, before they’re attacked by River’s father Harkness and a couple of henchmen.

Meanwhile Slow Horses’ boss Jackson Lamb (Gary Oldman) confronts Diana Taverner (Kristin Scott Thomas) about the Russian conspiracy that’s put his friends and colleagues in the crosshairs.

I’ve just finished watching Slow Horses Season 6 Episode 6.

I always trust Apple TV to deliver, but this? Dare I say the best season finale ever?? pic.twitter.com/CLYPVisG66 — Kay (@legendaarykay) October 21, 2026 After a lot of plotting and double-crossing, the episode ends with Ruth Bradley’s Emma dead and Rosalind Eleazar’s Louisa shot, but with the Russian threat eliminated.

Just before River gets to reunite with Sid though, he suffers a heart attack caused by a nerve agent and the last thing we see is his twitching foot through a doorway.

“ Slow Horses is living proof a show can be excellent AND released regularly,” wrote one fan.

“ Slow Horses the best ever.

What a fabulous season,” said another.

“Season 6 of Slow Horses just might be the best one yet, despite the body count.

Perfect mix of hilarity & tension,” added a third.

“ Slow Horses ’ season six finale was one of the best episodes so far, outstanding TV,” wrote another fan.