6 episodesFirst aired 29 November 2023
A romantic liaison in Istanbul threatens to expose a buried MI5 secret in London. When Jackson Lamb and his team of misfits are dragged into the fight, they find themselves caught in a conspiracy that threatens the future not just of Slough House but of MI5 itself.
E1Nov 202347m
A romantic relationship in Istanbul ends badly. Lamb hits the panic button when one of his Slow Horses fails to show up for work.
E2Nov 202344m
River has to steal something out of the Park to save a life. Lamb realizes a stranger game is afoot.
E3Dec 202347m
Marcus and Shirley face Lamb's wrath. River discovers revenge is a dish best served cold.
E4Dec 202348m
Tearney makes a bold move. The Slow Horses assist the Tiger Team, unaware of their hidden agenda. Lamb and Ho take a road trip.
E5Dec 202344m
Taverner and Tearney face off for control of MI5. River and Louisa find themselves caught in the crossfire.
E6Dec 202348m
The Slow Horses fight for their lives. Lamb shares some devastating truths with Catherine.