Season nine of long-running British spy thriller "MI-5" opens with Ros' (Hermione Norris) funeral, where Harry (Peter Firth) learns of a shocking betrayal at the highest level. Also this season, the agents go after Somali terrorist Hussein Abib (Peter Bankole), a scandalous secret from Lucas' (Richard Armitage) past is unveiled, and a growing bond develops between Ruth and Harry. Sophia Myles and Max Brown join the cast as agents Beth Bailey and Dimitri Levendis.

　　The stakes are raised in season two of "MI-5", as the threat to national security increases and the need to thwart the terrorists operating within the UK becomes more urgent. Tom is investigating a Serbian terrorist plot. His girlfriend and her daughter are trapped in Tom's house with a lap-top which is thought to contain a bomb. Meanwhile another bomb is primed to explode and this one kills the Secretary of State for Northern Ireland. Adding to the possible dangers faced by other government officials, Tom learns from his American colleague that an assassin is in town, the CIA know about him but they haven't told MI-5.

　　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.

　　The British espionage drama "MI-5", provides more shocking twists and turns in its third season. Tom Quinn (Matthew Macfayden) disappears following a shooting and new man Adam Carter (Rupert Penry-Jones) rises to the challenge in Section B. After recovering from his injury, Harry (Peter Firth) tasks Adam with proving Tom's innocence. Later in the season Danny (David Oyelowo) and Zoe (Keeley Hawes) are sent on a mission that has tragic consequences for one of them.

　　In the fifth season of the British espionage thriller, Harry Pearce and Adam Carter begin to suspect that members of the British establishment are creating a crisis in order to bring about a change of government. In the opening episodes Juliet Shaw encounters a car bomb, and her life is changed forever. Plus we meet former MI-5, turned MI-6 officer Ros Myers (Hermione Norris), who discovers a shocking family connection to the season's game-changing conspiracy.

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

　　Season four of espionage drama "MI-5" finds the team reeling from the loss of Danny (David Oyelowo), but thrown back into action when a bomb detonates near his funeral. Zafar Younis (Raza Jaffrey) and Juliet Shaw (Anna Chancellor) are introduced to the show, in a story involving a potentially devastating terrorist attack in the capital. Later in the season Lyndsay Duncan guest stars as a former MI-5 officer with a deadly grudge, one which threatens the lives of everyone back at The Grid.

　　In season six of the British espionage thriller, the team are pushed to their limits, as the relationship between British and American security deteriorates and loyalties change. Adam and Ros fight against an emerging terrorist threat, and a deadly virus that could decimate London. This season breaks away from the case-by-case episodic format, with one dominant storyline tying all the action together.