During the Second World War, the Allies took elaborate measures to hide from the Nazis the fact that they had broken the Enigma code. It occurred to me that an interesting novel might be written about a hypothetical, top-secret military unit whose purpose was to run around the fringes of the war planting fake evidence intended to throw the Nazis off the scent. That was the kernel around which CRYPTONOMICON developed. Early in the project I decided to add in a second plotline set in the present day. The book alternates between the 1940s and the present in a way that many of its readers seem to enjoy!