A character presumed dead comes back
Sidonie Baker, the MI5 agent played by Olivia Cooke, reappears in the sixth season of the Apple TV spy drama after being absent for four seasons. In Season 1 she shared a flirtatious rapport with the bumbling River Cartwright, played by Jack Lowden, before a gunshot to the head apparently killed her. Her revival was not a complete shock: the character also returns in the novels by Mick Herron, and Apple's advance promotion for Season 6, which finished this week, made little attempt to hide her storyline.[S1][S2]
Much has shifted since Cooke's first stint. Slow Horses has become a hit, collecting a string of Emmy nominations and several wins along with a devoted audience, while Cooke's career has risen through a leading part in the fantasy epic House of the Dragon. That added prominence shapes her return to the ensemble as an event in its own right.[S1]
A night on the run from Russian agents
Season 6 places Sid and River on the run from Russian sleeper agents across a single tense night. Diana Taverner, the icy MI5 chief played by Kristin Scott Thomas, once placed her favored protégée Sid inside Slough House, the purgatory for blundering agents, as her eyes and ears. Diana then used Sid's identity to cover an off-the-books assassination on Russian soil, and the Kremlin now seeks revenge. Every Slow Horses employee, past and present, becomes a target, and Sid turns to River for help.[S1]
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The pair's journey takes them from the family estate of River's deceased grandfather to Diana's seaside home, which Gary Oldman's Slough House chief Jackson Lamb wryly commandeers as a safe house. River and Sid smash through a barn, an arcade and at last an airstrip, where Sid comes close to being shipped off to Russia as a sacrifice against her will before the two finally share a kiss. The win proves short-lived: River gets Sid away and nearly reunites with her at his grandfather's house, yet he crumples in the kitchen, apparently poisoned, as she takes a shower upstairs in the finale's last moments.[S1]
Rebuilding a character after trauma
Cooke said River has kept Sid going in a sense. She described needing to recall how the character sounded, including the accent she had used, and welcomed the room to drop the more cheerful version of Sid seen in Season 1, since both Sid and River have matured and the events surrounding her disappearance were traumatic.[S1]
With little screen time for the three years Sid spent away, Cooke and director Adam Randall built a backstory of their own. They imagined her recovering at a secret MI5 rehabilitation facility for former spies, relearning how to walk and talk in an isolated process that left part of her closed off, in a location they pictured as perhaps Cumbria, green but easy to vanish into. Cooke also recalled the jealousy of watching seasons she was not part of, and the fun of a set she was eager to rejoin.[S1]
