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.

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

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

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

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

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

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.

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

Impossible decisions are faced and sacrifices are made.