I had done research on the art historian Anthony Blunt, who was a spy, which resulted in The Surveyor. A spy is never alone.
From Blunt I came to his small network of the Cambridge Five, which branched out more and more into a large network of espionage in the Cold War era.
You can illustrate this network with names and their connections. But how do you show spies themselves? Strictly speaking, I cannot recognise spies at all.
The faces of my spies are only visible from a few angles if you look very closely.
The pictures were created by putting hundreds of holes in them, like a punch code.