Alvin, AKA Secret Agent K-21 1/2, accidentally finds a message written in a secret code. Is someone spying on the defense plant in town? He sets out to solve the mystery with his trusty sidekicks Agent Q-3 and The Pest. Soon, he begins learning about ciphers, codes, and codebreaking with the help of a retired and bedridden WWII spy, which allows him to solve the mystery. Meanwhile, a new puzzle has arrived with one Miss Fenwick, a mysterious Mr. Smith, and a cryptic message.
Today, it seems like novels for kids have followed Hollywood in introducing some exciting event first and then sharing bits about the characters as the story evolves while keeping up the excitement. Alvin's Secret Code was written before that storytelling development and introduces the characters first, so it seems a bit slow to get started. However, the action gets going around the third page and the story is fairly well-paced after that.
The story introduces substitution ciphers, codes, scytales, and symbol ciphers. There is even an appendix with additional information on cryptography, including key word substitution ciphers, the Alphabet Box, and a common Civil War cipher. The appendix also includes frequency tables of letters and some hints on how to break ciphers along with a few practice exercises.
Hicks was a professional writer and editor for most of his life, but in WWII he served as a USMC officer on Guam and Bougainville and, according to Wikipedia, earned the Silver Star. In his biography at the back of the book it states that "In the service he learned something about codes and ciphers, a subject he had studied briefly in college." My guess would be that he did something in intelligence, but a short search didn't turn up anything more specific.
If you know kids who like solving puzzles, I would recommend this book.
Update: To make this review a little less sketchy, I'll add that the story part is only about 132 pages long, and the appendix adds about 15 pages. I read it all in 2 evenings, and I enjoyed it as well, even though I'm considerably older than 12.
