The fourth season of Apple TV+'s acclaimed series 'Slow Horses' has premiered, focusing on River Cartwright's new mission and the challenges he faces amidst chaotic developments. River, played by Jack Lowden, is revealed to be alive despite previous suspense, and his investigation takes him to France, raising questions about his competence in the field. The season adapts Mick Herron's novel 'Spook Street', featuring a blend of dark humor and thrilling espionage, with Gary Oldman reprising his role as Jackson Lamb, the beleaguered head of MI6's Slough House. New threats emerge, including a terrorist bombing in London, complicating the agents' already precarious situation. Critics have praised the show's reliability in maintaining high quality and engaging storytelling, despite its rapid release schedule. With returning and new characters, including Hugo Weaving as a mysterious antagonist, Season 4 promises to delve into the complexities of loyalty and betrayal within MI5.