Season seven of British spy thriller MI-5 opens with Adam Carter (Rupert Penry-Jones) valiantly battling to move a car bomb away from a densely packed memorial service. Meanwhile Harry secures the release of Lucas North (Richard Armitage), a MI-5 officer imprisoned in Russia for eight years. It's not long, however, before Ros begins to suspect Lucas' loyalties. The rest of the season deals with a top secret Cold War-era operation named Sugarhorse.