The Slow Horses fight for their lives. Lamb shares some devastating truths with Catherine.
Taverner and Tearney face off for control of MI5. River and Louisa find themselves caught in the crossfire.
Tearney makes a bold move. The Slow Horses assist the Tiger Team, unaware of their hidden agenda. Lamb and Ho take a road trip.
Marcus and Shirley face Lamb's wrath. River discovers revenge is a dish best served cold.
River has to steal something out of the Park to save a life. Lamb realizes a stranger game is afoot.