Olivia Cooke Returns to Slow Horses as Sid Baker, Four Seasons On
Olivia Cooke is back in Slow Horses, the British spy series on Apple TV, after a four-season absence. She announced her return with a single line: "Hello, River."
Cooke plays MI5 agent Sidonie "Sid" Baker. The character appeared briefly in Season 1 and was believed dead after a gunshot wound to the head. She is alive in Season 6, and Apple promoted her storyline ahead of the season. Sid also returns in Mick Herron's novels, the books the series is based on. Decider reported in September that her comeback would come in Season 6, Episode 2.
The new season follows Sid and River Cartwright as they run from Russian sleeper agents, people who have lived undercover in another country for years until they are activated. According to Variety, Diana Taverner used Sid's identity as cover for an off-the-books assassination on Russian soil. In another storyline, Sid is nearly shipped to Russia as a sacrifice at an airstrip. River helps her escape.
The season finale, "Judgment Day," is dated 21 October 2026 in Apple TV's press listings, and it is streaming on Apple TV. Apple's press description says the safe house becomes unsafe as Lamb and Taverner finally join forces. Variety reports that the episode ends with River collapsing from an apparent poisoning in his grandfather's kitchen, while Sid showers upstairs.
Cooke's profile was already large before her return to the show. Her career took off with a leading role in the fantasy series House of the Dragon. In the 2021 film Sound of Metal, she played Lou, the girlfriend and bandmate of drummer Ruben, played by Riz Ahmed.
Slow Horses has received a raft of Emmy nominations and a few Emmy wins over its run. In a recent interview with the Sydney Morning Herald, Cooke described Sid as having "disappeared" after Season 1 before returning in Season 6.
For viewers, the practical point is simple. Sid is back on screen, River is in danger at the end of the season, and the finale is available on Apple TV now.
