Let me just say that the subtitle is not kidding. This books covers codes from the ancient Greeks, through Caesar, Samuel Morse, Alan Turing, and up to the current day. Each chapter discusses the methods used to keep messages secure over the ages - from writing them on paper to be swallowed, sharing special code words, supercomputers using prime numbers to create encryption, and even biometric security. There are activities throughout the book that challenge readers to try their own skills at the various forms of deciphering and code breaking.
Photos of figures like Morse and Turing, as well as devices like cipher disks, the Enigma machine, and Bletchley Park's Bombe (the machine that cracked the Enigma code), add interest and reinforce that these are historical facts. There are also jokes such as, "Why don't Vikings send emails? They prefer Norse Code."
Sidebars provide information on the Code Talkers of WWII, as well as the women and African Americans who served as cryptoanalysts during the war. There is also information on the coded telegrams that Abraham Lincoln used to communicate with the Union Army. Readers may visit https://www.zooniverse.org/projects/zooniverse/decoding-the-civil-war to volunteer their help to decode Civil War telegrams and add them to archives.
If you have middle grade readers who are interested in mathematics or codes, this is the next book you need to show them. I read an ARC, but publication is scheduled for March 26.