The acclaimed British espionage thriller Slow Horses has consistently blended shadowy spycraft with dark workplace humor for three seasons on Apple TV+, with a fourth season on the way. Adapting author Mick Herron's novels, the series follows a group of disgraced intelligence operatives who are relegated to Slough House, an office that handles the thankless and menial bureaucratic tasks in the British government's intelligence apparatus. Among Slough House's more frustrated recent recruits is River Cartwright, whose promising career was sidelined after publicly screwing up a training exercise.