Tours languages that hide meanings from all but a chosen few, explains the difference between ciphers and codes, and shows how secret messages have been written and broken for years.

"Codes can carry big secrets! Throughout history, lots of good guys and lots of bad guys have used codes to keep their messages under wraps. This fun and flippable nonfiction features stories of hidden treasures, war-time maneuverings, and contemporary hacking as well as explaining the mechanics behind the codes in accessible and kid friendly forms. Sidebars call out activities that invite the reader to try their own hand at cracking and crafting...

Geronimo investigates to see if the famous painting Mona Mousa holds a secret code.

Amy and Dan cross the oceans on the trail of a famous aviator, but they find more than they're looking for. Their enemies are becoming more vicious, and the truths they discover more crushing than ever.

Unable to return to their normal lives despite the end of the Clue hunt, new Madrigal leaders Amy and Dan anxiously prepare for a retaliatory strike by the Vespers, who kidnap a number of Cahill family members and demand that Amy and Dan steal a famous painting.

When a rare coin and a strange code are uncovered in McKenna School, Malcolm and the other classroom pets of the Midnight Academy take on their most challenging assignment yet and, through their investigations, they just might save the school from closing.

"One girl must unlock the secrets within Paradise Lost to save her father's life"--