Dec 20, 2013 Updated: 2:13 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
Ros infiltrates the office of a financier who may be plotting to bring down the British economy; Connie is suspected of being a Russian mole and is placed under house arrest.
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