This is a fun little puzzle book with some challenging puzzles. This isn't actually written by Bruce Coville. It is more like a book which complements the series. It begins as a challenge from the three characters (Susan, Peter, and Duncan) that are featured in Bruce Coville's alien books. You have one week to decided if your teacher and even some of your classmates are possibly aliens. Each day of the week is mapped out with puzzles, codes, and mini mysteries that you need to decipher. I enjoyed figuring out the puzzles and believe that this book would be a fun extra credit activity to the Coville books if a teacher is reading the series in class. ( )