Before 'House of the Dragon': Olivia Cooke Shined as the Scene-Stealing Spy in Slow Horses

Olivia Cooke may have rocketed to worldwide fame as Alicent Hightower in HBO’s House of the Dragon, but her talent was already well established long before she entered the world of Westeros. While Cooke’s portrayal of the ambitious and complex Alicent won her global attention, fantasy fans might not know that Cooke briefly showcased her impressive range in the British spy thriller Slow Horses, the same year that House of the Dragon debuted. Cooke’s turn as MI5 agent Sidonie “Sid” Baker in Slow Horses may have been short-lived, but it left a lasting impact, proving that she could hold her own in a star-studded ensemble.

A Hidden Gem in the World of Spy Dramas

Slow Horses, based on Mick Herron’s popular Slough House series of novels, debuted on Apple TV+ in 2022. The show is a darkly comedic spy thriller that follows a group of disgraced MI5 agents relegated to Slough House, a purgatory-like division for those who have committed career-ending mistakes. Led by the gruff and slovenly Jackson Lamb (played by the legendary Gary Oldman), the agents—nicknamed the “Slow Horses”—are seemingly doomed to spend their days in bureaucratic misery. That is, until they find themselves thrust into an actual high-stakes conspiracy.

With a talented cast that includes Gary Oldman, Jack Lowden, and Kristin Scott Thomas, Slow Horses has garnered critical acclaim and built a devoted fanbase. As the show heads into its fourth season, Cooke’s early appearance as Sidonie “Sid” Baker in the first season remains one of the series’ standout performances.

Olivia Cooke as Sidonie “Sid” Baker: A Standout in Slow Horses

In Slow Horses, Cooke plays Sid Baker, a character who immediately stands out from the rest of the Slough House misfits. Unlike her bumbling and disgraced colleagues, Sid is sharp, competent, and resourceful—so much so that it’s quickly clear she doesn’t belong at Slough House. In her very first scene, Sid effortlessly outsmarts a journalist during a covert operation, stealing crucial information with finesse. Her skill is even recognized by MI5’s higher-ups, with the Deputy Director calling her the “most capable” agent among the Slow Horses.

Cooke’s portrayal of Sid is equal parts dry, sardonic wit and cool professionalism. She exudes confidence, knowing full well that she’s more talented than her peers, but she also maintains a sense of detachment. While the rest of the agents at Slough House are desperate to prove themselves, Sid seems amused by the absurdity of their situation. Her dynamic with Jack Lowden’s River Cartwright, who is eager to redeem himself after a major public blunder, is particularly compelling. While River is all intensity and determination, Sid is the calm and collected foil, giving their scenes together a delightful contrast.

Sid’s Tragic Exit: A Loss for Slow Horses

Unfortunately, Sid’s time in Slow Horses is cut tragically short. Despite being the most skilled agent in the group, Sid is shot in the head while on a mission, leaving her in a coma for several episodes. In a gut-wrenching turn of events, Sid is later revealed to have died in the hospital, much to the dismay of fans who had hoped to see more of her character. Cooke’s brief but memorable performance left many viewers wanting more, as Sid’s sharp-witted persona had quickly become a fan favorite.

However, Sid’s death isn’t as straightforward as it seems. In the final moments of Season 1, the Slough House agents discover that all records of Sid’s existence have been mysteriously erased, raising questions about whether she is truly dead or if there’s more to her story. This revelation has sparked speculation that Cooke’s Sid could return in a future season, especially since the Slough House novels see Sid reappear in later books.

With House of the Dragon catapulting Olivia Cooke into the spotlight, fans of Slow Horses have been left wondering if she might reprise her role as Sid. Given that Sid’s fate was left ambiguous and the character returns in Mick Herron’s novels, there’s reason to believe that Cooke could make a comeback in future seasons. However, with Cooke’s growing popularity and busy schedule, her return remains uncertain.

Still, her short stint in Slow Horses remains a testament to her versatility as an actress. From navigating the political intrigue of Westeros to playing a no-nonsense MI5 agent, Cooke has proven time and time again that she is capable of commanding the screen, no matter the genre.

While Olivia Cooke’s portrayal of Alicent Hightower in House of the Dragon may be her most well-known role, her performance in Slow Horses is a hidden gem that showcases her comedic timing and dramatic range. As Sid Baker, Cooke effortlessly captured the essence of a capable agent trapped in a division of misfits, and her brief but powerful performance left an indelible mark on the series. Whether or not Cooke returns to Slow Horses, her role as Sid will remain a standout in her already impressive filmography.