Nov 21, 2014 Updated: 3:36 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
Louisa dumps Martin after he makes an inappropriate remark, but he receives a second chance when Louisa calls on him to help an injured friend.
Find out about upcoming shows and events. Enter your email address below.