Mar 7, 2014 Updated: 9:40 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.
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