Slow Horses Season 6, Episode 5, titled “Sayonara,” sees River Cartwright rescue Sid Baker from Russian assassins, only to discover that Diana Taverner has agreed to hand her over to Russia. Released on October 14, 2026, the penultimate episode also brings another major death and sets up a dangerous confrontation ahead of the season finale.
Spoiler Warning: This recap contains major spoilers for Slow Horses Season 6, Episode 5.
Slow Horses Season 6 Episode 5 Recap: River Rescues Sid From the Assassins
The episode picks up immediately after J.K. Coe’s death, with Russian assassins Jim and Jane holding Sid captive. River is following them in a borrowed vehicle, determined to reach Sid before they kill her.
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However, Sid creates her own opportunity to escape. She attacks Jane with a souvenir licence plate magnet, causing their car to crash. Jane appears dead, while Sid manages to escape into the nearby woods.
Jim survives the collision and follows her. He eventually catches Sid near a lake and attempts to drown her, but River arrives just in time to intervene.
During the violent struggle, Sid strikes Jim with a rock before she and River overpower him and drown him in the water. His death brings an end to the immediate threat from the assassin who killed Coe in Episode 4.
However, Jane’s body later disappears from the crashed vehicle, raising questions about whether she survived.
Why Does Diana Taverner Betray Sid Baker?
After escaping the assassins, River and Sid are collected by MI5’s Dogs. Instead of returning them to the Park, the agents take them to a private airfield.
River soon discovers that Diana Taverner has arranged to surrender Sid to Russian intelligence.
The arrangement stems from an unofficial assassination operation in Kazan, which triggered the Russian retaliation against British intelligence. Diana wants to protect the agent responsible for the original killing and has decided that Sid is an acceptable sacrifice.
When Sid confronts Diana over the phone, the First Desk makes her position clear. The exchange will proceed, even though it leaves Sid facing an uncertain future in Russian custody.
The planned flight to Sofia, Bulgaria, also offers little reassurance about what might happen once the Russians take control.
Diana’s decision exposes how far she is prepared to go to protect her position and contain the consequences of the Kazan operation.
Jackson Lamb Uncovers the Connection to Damien Cantor
Meanwhile, Jackson Lamb continues investigating the conspiracy behind the attacks on Slough House.
He connects Damien Cantor’s financial interests to Frank Harkness and the effort to eliminate people who could expose the operation. Lamb also confronts Diana about her involvement, making it clear that he understands the wider conspiracy.
Elsewhere, the remaining Slow Horses stay hidden at Diana’s holiday home while Roddy Ho investigates Cantor’s movements.
His research leads to Natasha, a Russian intermediary involved in Cantor’s major media distribution deal. Her apparent intelligence connections give Lamb another reason to question what Cantor is planning.
These developments suggest that the financial arrangement and the attacks on Slough House are connected, although the full extent of the conspiracy remains unresolved.
Slow Horses Season 6 Episode 5 Ending Explained: What Happens to River and Sid?
The episode ends with River refusing to let MI5 deliver Sid to the Russians.
After sharing an emotional goodbye that reveals their growing feelings for each other, the pair manage to escape their guards at the airfield.
However, River eventually realizes that Sid needs more time to get away. He decides to turn back and distract the pursuing agents, allowing her to continue escaping.
River is surrounded and captured by the Dogs, leaving his fate uncertain.
His decision also creates a serious problem for Diana, whose carefully arranged exchange has fallen apart.
The ending leaves several questions for the October 21 finale: Can Sid escape the country safely, what will happen to River, and can Lamb expose the people responsible for the Kazan operation?
With Jane’s whereabouts still unknown and Frank Harkness involved in the wider conspiracy, the remaining threats are far from resolved.
Slow Horses Season 6, Episode 6 premieres on Wednesday, October 21, 2026, on Apple TV.
For additional background, see Apple’s official Season 6 announcement and Decider’s coverage of Jim’s death.
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