Black Bag

Writer David Koepp said he found that, although all the spycraft was very cool, he learnt more about the people than he ever expected. He added that one woman told him her job made it impossible for her to sustain a relationship. A line in the film grew out of his conversations with her: 'When you can lie about everything, how do you tell the truth about anything?'. Koepp went on: 'Think about it. If you want to have an affair, it could not be easier. You just say, "I'll be away for three days and you cannot ask me where I'm going because you do not have clearance." You cannot trust people and people cannot trust you. For George (Michael Fassbender) and Kathryn (Cate Blanchett), the confidential information they cannot share is kept in what they call their "black bag".'