Screenwriter Tom O'Connor found out as much as he could about Greville Wynne and Oleg Penkovsky. Their relationship is mentioned in several books but only in fragments. "There's enough to understand the basics," O'Connor stated. "A lot of the events were and remain classified, and so sometimes, finding out what exactly happened was a challenge because there is active misinformation being put out by both sides. People don't necessarily want everything on-the-record."
Piecing the story together from various sources, screenwriter Tom O'Connor wrote the draft on spec and sent it out to production companies. It landed on the desk of Ben Pugh of production house 42 who immediately knew he wanted 42 to produce the film. "I wanted to make a movie like this for a long time," said Pugh. "I love that period. I loved the idea of an everyday guy in the center of that world with all these thrilling elements and this massive global political backdrop while it's about him and his family, and he ends up trying to save the world."
Greville Wynne wrote an autobiography which was first published in 1967 entitled 'The Man From Moscow: The Story of Wynne and Penkovsky.' The story was later adapted for TV by the BBC as The Man from Moscow (1985). However, screenwriter Tom O'Connor was aware that the reliability of this book had been questioned. O'Connor said: "I read a few people who did a point-by-point discrediting of the things that Wynne claimed happened arguing that they couldn't possibly be real."
FilmNation took the packaged film to Cannes in 2018, where it was met with enthusiasm. "The reception was very healthy because it's a spy film that felt like it had something new and timely to say," said producer Ben Browning. "There's a long history of successful great Cold War thrillers, the difference here is that rather than being about inscrutable people with inscrutable motives it has a clear emotional heart, and it's essentially about a relationship between two men who did something extraordinary."
Benedict Cumberbatch's third film concerning British intelligence, and the second of those films to be set during the Cold War. He previously appeared in Tinker Tailor Soldier Spy (2011) and The Imitation Game (2014).