Sep 17, 2014 Updated: 1:44 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
Martin and Louisa's engagement excites the town, but the news is overshadowed by a mushroom-caused aspergillosis outbreak. Meanwhile, Bert's restaurant faces financial calamity.
Find out about upcoming shows, special events, and discounts.