Assemble a double-security lock with a combination code and key to hide your most prized possessions. Then use the included buzzer and electronic components to build a really working door alarm or pressure plate to keep your valuables from prying eyes. With easy-to-find materials from home and our step-by-step instructions in the book, you'll find even more spy activities such as dusting for fingerprints, encrypting and decrypting codes, making diversion decoys, and more!