During World War II, countries on both sides of the conflict created complicated codes to send secret messages that the enemy wouldn't understand. They used codebooks, complex machines, and complicated languages. In the United States and Britain, thousands of men and women worked behind the scenes to create these codes and to study and decode messages sent by the enemy. These code breakers cracked the codes of Germany and Japan, which ultimately led to Allied victory and shortened the war by several years. Find out more about the men and women who used their skills in languages and mathematics to serve their countries. Book jacket.