Wartime Spies
A series of six educational books for children age 10 and up.
This series design was heavily inspired by flip clocks and the Enigma Machine (a device used for code breaking in WWII). Both devices have an elusive quality that speaks to the essence of what it means to be a spy across time. A meticulous reader will notice a code hidden in each book, decipherable with just a bit of cryptanalyst-like research.
Publisher: The Creative Company
Author: Michael E. Goodman