First- the ancient Greeks hid secret messages under their hair. Then- Mary Queen Of Scots completely lost her head because of a cracked code. Now- computers create codes no human can crack. This revealing guide gives you the key to unlocking the secret languages of spies. Get on the case to discover how to decipher dots and dashes- fanthom flags and solve a simple cipher. Find out how codes shaped history- won wars and might even help us talk to aliens. Plus- try your hand at code-breaking. Will you crack under pressure?