6 episodes · 2002

Defending their country, deceiving their friends - it's all in a day's work for the agents at MI5, the Security Service. The elite team tackle organised crime, espionage and terrorist activities, as well as the conflicts and power struggles back in the office. There's a car bomb in Liverpool, a siege in the Turkish embassy and the murder of a double agent, not to mention the difficulty of having to lie to loved ones about who you are and what you do.

10 episodes · 2003

The second series gets off to an explosive start, picking up at the exact moment the first one finished. MI5 agent Tom's girlfriend Ellie and her young daughter are trapped inside a securely sealed house in which a bomb is about to explode, and there's no way out. There's also organised crime, terrorist activities, embassy sieges, weapons proliferation, subversives, anarchists and drug traffickers, not to mention the conflicts and power struggles the elite team has to deal with back in the office.