What Happens in the Field, Stays in the Field: David Koepp Discusses His New Thriller ‘Black Bag’

Espionage films are notoriously delicious. Black Bag--the new spy thriller written by David Koepp, is no exception. In this taut tale of British intrigue, National Cyber Security Centre agent George Woodhouse (Michael Fassbender) is tasked with ferreting out a mole within his own organization, suspected of leaking malware to oppositional forces. His five chief suspects happen to include his wife Kathryn St. Jean (Cate Blanchett), with whom he shares a vibrant marriage, despite - or maybe because of the secrecy baked into their relationship. Before either of them leaves on out-of-town business, they need only utter the phrase “Black Bag” to invoke their longstanding no-questions-asked policy.

None of this deters George’s attempt to get to the bottom of the leak by any means necessary—a task easier said than done. After all, polygraphs can be easily beaten, and mandatory psych evaluations are less-than reliable, especially since the in-house therapist is also a suspect.

Which brings us to the intimate dinner party George throws in an effort to snake out the culprit—group interview style. Part of the fun stems from the fact the guests know full well they’re under a microscope, yet they’re equally masterful at deflection. It makes for one hell of a six-man chess match where alliances emerge, jealousies flare, and steak knives are plunged through the backs of hands. Hey, decorum can only last so long.

David Koepp spoke with Andrew Bloomenthal about penning this crackling thriller.

This interview has been edited for content and clarity.

ANDREW BLOOMENTHAL: How would you describe Black Bag?

DAVID KOEPP: Black Bag is about a pair of married spies who have to decide if the marriage is more important than loyalty to their country. I thought of this idea thirty years ago - the longest I’ve ever gestated anything. I was in the middle of writing the first Mission Impossible, doing a lot of research, and I was talking to a CIA guy about his personal life because I found that to be much more interesting than the spy crap, and I remember him telling me it was impossible for intelligence agents to sustain a relationship because it’s too easy to have an affair and cover your tracks. 

I knew immediately that I wanted to see that in the context of a marriage rather than someone trying to date and find the right person, because by definition a marriage is meant to be a settled relationship. By introducing this element, where these married spies are limited about what they can talk about with each other, it causes uncertainty.

ANDREW: After you initially proposed the idea to director Steven Soderbergh, how did the writing process go? Did you present a finished draft, or did he give you notes along the way?

DAVID: I wrote this during the writer’s strike when I had four or five months on my hands. I always wanted to pursue this idea and suddenly I didn’t owe anyone anything so nobody knew about this complicated story that I had the luxury of working out in private. The script was in a pretty advanced state when Steven got it, which is great. That’s why I like working on spec, when it goes well. Sometimes it doesn’t go well and you’re stuck with a script nobody wants forever.

ANDREW: You embedded this story in the NCSC—the National Cyber Security Centre--an actual British organization. Was it a given that you were going to plug into a real entity, or did you contemplate inventing a fictitious organization?

DAVID: I didn’t want it to be fictitious because you can usually spot that. The NCSC is part of the Government Communications Headquarters (GCHQ) which is the main UK intelligence organization - similar to the NSA in the US, so I just set it in the British counterpart.

ANDREW: And you shadowed members from that group. What are some nuggets you learned?

DAVID: One of the things that surprised me was the vast ocean of information that now pours in every second to our intelligence-gathering community. There’s so many phone calls to listen to and so much data, that we really rely on algorithms - and now AI to sort out what might be of interest to us, before the human interpreters even get involved. 

But then a lot of our best and brightest young people in the intelligence community show a facility with a foreign language—Arabic or Farsi or Russian or Chinese, so these organizations park these people in a room and have them listening to wiretaps every day. That intelligence is OK, but nothing replaces direct human intelligence, which is starting to be something of a lost art.

ANDREW: And we should say that the NSCS’s main mission is to gather intelligence through technology rather than through human assets. But then in the movie, certain characters break form and rendezvous in the field to exchange information.

DAVID: It would be a boring movie if they didn’t. And to be clear, some people are operational, out there doing things - not just sitting back and monitoring.

ANDREW: The plot centered around leaked malware that could destabilize nuclear facilities. When did you realize you could hinge the narrative on that detail?

DAVID: Fairly early on, but I’m much more interested in the fucked up personal lives of the six main characters and the marriage around which everything else revolves, so you want a MacGuffin that’s simple and powerful, because it’s about the characters more than the thing itself, as Hitchcock said.

ANDREW: The film opens with an elaborate cooking sequence with George preparing a huge meal, with close-ups of him searing meat and deglazing pans. Did you specifically describe these actions in the script or did you simply write, “George cooks up a storm?”

DAVID: Somewhere in between. I don’t go into all the specifics, but I think it’s an abdication of screenwriter responsibility to say, “George cooks up a storm,” and leave it at that. Should it be a full minute of him cooking? Is it a single shot of him stirring a pot? What are you trying to express? In my case, I was trying to express how specifically George does everything. And the fact that he’s good at chopping things means his focus is intense. 

But in this case, I also wanted the specific shot of his glasses fogging up when we first meet him for the obvious metaphor. So you have a responsibility as a screenwriter to describe these things as fully as you want them to occupy screen time. If you feel it’s twenty seconds, maybe it’s a third of a page. That said, don’t bog the script down with unnecessary direction because there’s nothing worse than a slow read.

ANDREW: The final act featured the use of a gun. Did it matter to you what kind of gun was used?

DAVID: You never want to just say, “He pulls out a gun.” You want to say what kind of gun he pulls out, and that’s easy research—just Google it up. You’ll find your answer in thirty seconds, knowing the armorer and the actor and the director may decide they want a completely different kind of gun, and that’s fine. But specifics in a script are always better than generalities, so if he pulls out a "Glock Blah Blah Blah," say that.

ANDREW: The film also heavily featured polygraphs. Can you really beat the poly by clenching your anus?

DAVID: You can! Clenching your anal sphincter muscle evens out your responses. Your heart rate and blood pressure are steadier—a good thing to know if you ever have to lie on a polygraph.

ANDREW: Finally, is the term “Black Bag” actual vernacular used in espionage circles?

DAVID: No. I think I made that one up. I remember hearing about a filmmaker, and if he really hated a take, he’d say, “That goes in the black bag,” which meant to put the negatives in a black bag and throw it in the East River where no one will ever see it. I like the Black Bag as a place where secrets go, so I made it up as slang that they used to communicate with each other. “Sorry, can’t tell ya. Black Bag!”

Black Bag releases only in Theaters on March 14, 2025.