The eighth season of the British spy series &quotMI-5,&quot which follows secret agents as they foil evil plots around the globe, begins with the fallout from Harry&#39s kidnapping by the Russians. A mysterious organization known only as &quotNightingale&quot is the ongoing focus of the eight episodes. And Lucas&#39 relationship with CIA agent Sarah Caulfied (Genevieve O&#39Reilly), reignites concerns over his loyalty. This season also sees the exit of one of the few original cast members, Malcolm Wynn-Jones.