This intriguing and revelatory history of cryptology ranges from the early days of code-making and code-breaking in ancient Egypt, Sparta, and Rome to the present day when it has slipped beyond the tight control of governments and now affects all our lives whenever we use our cell phones or connect to the internet. Subjects covered here include Mary Queen of Scots’ cryptic messages when she was plotting against her cousin Elizabeth I; the codes used by George Washington for military and political purposes; and code-breaking during World Wars I and II, including the Enigma Machine. Those who invent codes and those who break them are fascinating characters. This is their story.