Olivia Cooke on Returning to ‘Slow Horses,’ On-Set Injuries and That Shocking Finale Cliffhanger: ‘I Want a Showdown!’

Olivia Cooke has returned as MI5 agent Sidonie Baker in the sixth season of “Slow Horses”, after her character was presumed dead in the first season. Sid’s return matters to the story because she and River Cartwright are forced to flee Russian agents, while the finale leaves River apparently poisoned and their reunion uncertain.

Sid’s identity was used by Diana Taverner to cover an unauthorised assassination in Russia, prompting retaliation against the Slough House agents. During one night, Sid and River travel from his grandfather’s house to Diana’s beach retreat, escaping several threats and sharing a first kiss. Cooke describes returning to the series after years away and filming more than a month of night shoots; the article also discusses on-set injuries and her work with Jack Lowden.