Offering an introduction to the world of secret writing and coded messages, this book contains simple instructions on how to make 12 different code and cipher machines. Some of them are based on devices that have been used by spies for centuries and all of them can be made by using a pencil, scissors, card and glue. There is additional information about each code, including ways of complicating it so that it becomes indecipherable even to other readers of the book.