Oct 1, 2014 Updated: 10:59 AM
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
Ruth finds herself on the wrong end of an investigation after witnessing a man commit suicide; Harry directs the team to investigate a fire at Cotterdam Prison that killed seven terror suspects.
Find out about upcoming shows, special events, and discounts.