Slow Horses Season 5: River and Louisa's kiss arrives amid messy, book-faithful tension

In its Season 5 premiere, Slow Horses delivered a long-anticipated moment: River Cartwright and Louisa Guy share a kiss. Showrunner Will Smith had warned fans that the two would test the boundaries of friendship in a Slow Horses way, and that the moment would be messy. The scene follows Louisa’s decision to leave Slough House and the service after a conversation about loss and trauma — Min Harper’s death and River’s own father issues — pushing River to a moment of emotional vulnerability. After Louisa reveals her plan, River, who had believed she was taking a six-month break, misreads the situation and leans in. The kiss is awkward, earnest, and emotionally charged, and the two quickly realize they are not simply acting on a spark but wrestling with years of unspoken pain.

The fallout is immediate and human. Louisa questions the impulse, noting that a woman opening up about feelings can be misread as a signal for sex. River denies any ill intent, but the moment leaves both characters unsettled. A phone call interrupts the scene before it could resolve, and River agrees to give Louisa space. The moment serves as a reminder that the series remains faithful to the books’ dynamic: romance does not eclipse the central tension of teamwork, loyalty and shared trauma.

Smith has repeatedly explained that while viewers may root for River and Louisa, the show will stay true to the character dynamics and not force a romance that the source material does not fully support. He told Decider that “it’ll be in a Slow Horses way, and it will be messy.” The pair’s chemistry has long been noted by cast and crew, including an improvised car hug in Season 3 that director Will Smith praised for its authenticity.

Industry observers say the kiss marks a turning point in Season 5’s approach to personal relationships against the backdrop of espionage. New episodes of Slow Horses premiere Wednesdays on Apple TV+.