The author presents case histories of persons whose lives have been blighted by our uniquely American faith in the myth of the lie detector. Dr. Lykken also explains how to "beat" the machine, not only because it is unfair that spies and Mafia soldiers already know these techniques, but also because innocent persons have nearly a 50:50 chance of failing lie detector tests unless they use appropriate countermeasures. Many state courts in the U.S. still admit lie detector tests into evidence under certain conditions - a practice that ensures the conviction of more innocent people every year. Finally, Dr. Lykken reports on the results of recent surveys of informed scientific opinion about lie detection and presents another method of polygraphic interrogation that is designed to detect, not lies, but the presence of guilty knowledge. This method is scientifically credible and holds promise for future use in criminal investigation.