Johnny Worricker (Bill Nighy) is a long-serving MI5 officer. His boss and best friend Benedict Baron (Sir Michael Gambon) dies suddenly, leaving behind him an inexplicable file, threatening the stability of the organization. Meanwhile, a seemingly chance encounter with Johnny's striking next-door neighbor and political activist Nancy Pierpan (Rachel Weisz) seems too good to be true. Johnny is forced to walk out of his job, and then out of his identity to find out the truth. Set in London and Cambridge, this is a contemporary spy movie for the BBC, which addresses intelligence issues and moral dilemmas particular to the new century.