Totally: Cracking Codes by Diana Kimpton (author) and Mike Phillips (illustrator)

First the ancient Greeks hid 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 unlock the secret languages of spies. Get on the case to discover how to decipher dots and dashes, fathom flags, and suss a simple cipher. Find out how codes shaped history, won wars and could even help us talk to aliens. PLUS try your hand at code making and code-breaking. Will you crack under pressure?