Dec 18, 2013 Updated: 4:52 PM
A modern, edgy drama full to the brim with passion, politics and peril. MI-5 leads us into the dangerous world of Britain's top-secret security agency, and into the lives of people who must lie, and sometimes die, for a living.
VISIT THE BBC's MI-5 WEB SITE
Section D is joined by an FSB officer in the hunt for a nationalist from the ex-Soviet state of Azakstan, who's trying to procure a nerve gas.
Find out about upcoming shows, special events, and discounts.