Book excerpt: Sh-h-h-h-h-h!! Top Secret... Crack the code of superspy science fun! Make your own spy sunglasses * Write messages with invisible ink * Hook up a secret alarm, and much more! Discover how spies use science to keep--or uncover--top secrets.Learn how to go under cover, master Morse code, and even builddevices to see and hear through walls! These and dozens of otherfun-filled activities give you an inside look at the science behindspy gadgets and tricks of the trade. All the activities arecompletely safe and can be done with everyday stuff from around thehouse.