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

River and Sid join forces. A misfired gun has dire consequences.

Lamb liaises with a Russian defector who may hold a clue to sleeper agents. River is on the trail of a ruthless assassin.

Jackson Lamb is on high alert after a former spy is found dead. Min and Louisa are tempted by an offer from outside Slough House.

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

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

A naive agent makes a discovery about the Westacres bomber. Lamb suspects that David knows more than he's letting on.

River is trapped in France. Back at Slough House, the Dogs have come for Lamb.

Taverner is desperate to hide dangerous secrets. River seeks answers at his grandfather's house.

The Slow Horses must disappear to avoid capture by MI5. Lamb and River head to The Park to outwit Taverner.

Taverner and the Slow Horses attempt different approaches to locate the kidnappers and Hassan. Ho makes a shocking discovery about Sid.

River gets cozy in the Cotswolds while searching for a sleeper agent. Min discovers Russian drinking games are the most brutal of all.

Louisa makes her move on Pashkin. Catherine makes moves of a different kind when she plays high-stakes chess with a sinister stranger.

A romantic relationship in Istanbul ends badly. Lamb hits the panic button when one of his Slow Horses fails to show up for work.

River has to steal something out of the Park to save a life. Lamb realizes a stranger game is afoot.

Tearney makes a bold move. The Slow Horses assist the Tiger Team, unaware of their hidden agenda. Lamb and Ho take a road trip.

A London bombing puts Taverner under pressure. When River grows concerned for his grandfather, Louisa encourages him to go for a visit.

Lamb orders his Slow Horses to walk into traps. River believes something alarming is heading toward London.

Lamb and Katinsky go head-to-head. Ho finds himself trapped on a train with a Russian assassin.

Marcus and Shirley face Lamb's wrath. River discovers revenge is a dish best served cold.

The Slow Horses fight for their lives. Lamb shares some devastating truths with Catherine.

Lamb questions David about France as River comes face to face with the enemy.

Taverner and Tearney face off for control of MI5. River and Louisa find themselves caught in the crossfire.

Impossible decisions are faced and sacrifices are made.