
When a young man is kidnapped and threatened with beheading, the slow horses find themselves unexpectedly embroiled in a dangerous case that forces them to prove their worth.

River Cartwright is ousted from MI5 and finds himself in a place worse than purgatory: Slough House, dumping ground for failed spies.

Slough House is the unlikely venue for a secret romance, but events take a dark turn when a dangerous encounter becomes deadly.

Taverner sends the Dogs to hunt down Lamb and the Slow Horses. River holds the secret to saving the gang.