The film presents the gripping true story of Katharine Gun, portrayed by Keira Knightley, a dedicated employee of GCHQ (Government Communications Headquarters), who in 2004 courageously leaked a classified memo. This document revealed an illegal spying operation orchestrated by the United States to gather compromising information on United Nations diplomats who were set to vote on a crucial resolution concerning the impending invasion of Iraq in 2003.
Empowered by her conviction that then-Prime Minister Tony Blair was misleading the public about Iraq's alleged possession of weapons of mass destruction (WMDs), Katharine receives an alarming internal memo just days before the UN vote on January 31, 2003. This memo outlines GCHQ's covert surveillance of UNSC members, including countries like Cameroon, Angola, and Chile, and their voting intentions regarding the Iraq resolution. Her colleague, Andy Dumfries ([Jack Farthing]), discusses the implications of this memo with their boss Fiona Bygate ([Monica Dolan]), confirming their suspicions about the collusion between the US and UK to manipulate the second UNSC vote.
In her quest for justice, Katharine confides in her friend Jasmine ([MyAnna Buring]), an anti-war activist, who urges her to make the memo public despite the risks of being charged with treason under the Official Secrets Act. With determination, on February 3, 2003, Katharine copies the memo onto a floppy disk, prints it, and sends it to Jasmine, setting off a chain of events that would change her life forever.
At the forefront of this investigation is Ed Vulliamy ([Rhys Ifans]), an impassioned journalist frustrated by the lack of support from his editor, Roger Alton ([Conleth Hill]), for his pieces showcasing the truth about the Iraq war. As the story unfolds, Martin Bright ([Matt Smith]) and Peter Beaumont ([Matthew Goode]) join forces with activists, delving deeper into the implications of the leaked information and the ethical dilemmas it presents.
Their efforts culminate on March 2, 2003, when the memo is published, igniting panic in Katharine, who reveals her actions to her husband Yasar (Adam Bakri). Although the memo is met with skepticism due to spelling errors that compromise its credibility, Katharine remains resolute, leading to her eventual arrest. Despite the turmoil, including her husband facing deportation, Katharine gathers a formidable team of human rights attorneys, including Ben Emmerson ([Ralph Fiennes]), Shami Chakrabarti ([Indira Varma]), and James Welch (John Heffernan), who work tirelessly to defend her on the grounds that the war itself was illegal.
Elizabeth Wilmshurst ([Tamsin Greig]), a key witness who resigned from her role in protest against the war, adds further weight to their case. As they uncover the true motivations behind the war, it becomes evident that the government’s lies had far-reaching consequences. Ultimately, Katharine's trial takes an unexpected turn when the prosecution withdraws the case, perhaps realizing the political fallout from exposing the truths hidden within their own ranks.
In a somber reflection, by 2010, the documents are finally declassified, revealing the staggering human cost of the war, with over a million Iraqis dead and numerous British and American soldiers also losing their lives. This thought-provoking narrative emphasizes the sacrifice of a whistleblower in the fight against government deception.
