Kristie Macrakis combines a storyteller's sense of drama with a historian's respect for evidence in this page-turning history of intrigue and espionage, love and war, magic and secrecy. From the piazzas of ancient Rome to the spy capitals of the Cold War, Macrakis's global history reveals the drama and importance of invisible ink. From Ovid's advice to use milk for illicit love notes, to John Gerard's dramatic escape from the tower of London aided by orange juice ink messages, to al-Qaeda's hidden instructions in pornographic movies, this book presents spellbinding stories of secret messaging that chart its evolution in sophistication and its impact on history. The book includes fun kitchen chemistry recipes for readers to try out at home.