From the Bible Code to the indecipherable Voynich manuscript, from subtly altered hieroglyphs carved into ancient Egyptian monuments to clues hidden in Renaissance paintings, we are surrounded by mysterious codes bearing hidden messages from the past. Taking in the full history of code making, Stephen Pincock provides a fascinating insight into this most secret and mysterious of crafts, profiling Julius Caesar and Elizabeth I's spymaster Sir Francis Walsingham, while explaining how codes reached new levels of complexity in the Cold War.