Nov 25, 2014 Updated: 11:11 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
The Season 5 finale finds an environmental-terrorist group taking control of the Thames Barrier and threatening to flood London unless the government releases a top-secret document.
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