The "lie detector" is an American invention of the 20th century that measures the physical changes (blood pressure, sweat, hear rate) that are said to correspond to willful deception--lies. However, there are serious scientific and philosophical questions about whether willful deception can be unequivocally linked to specific bodily reactions, and about whether a device of this or any (known) scientific type can accurately measure and predict or proscribe results based on physical changes.
Alder's book covers these theoretical issues, as well as providing an interesting history of the three men most instrumental to the lie detector technology: John Larson, Leonarde Keeler, and William Marston, who went on to write the Wonder Woman comics with his wife--mother of two of his children--and his live-in mistress--mother of his other two children! As distant as that may seem from normalcy, amazingly enough, despite these twists or because of them, he handled the notoriety and the stresses of the position better than either Larson or Keeler.
Alder spends considerable time placing the device in America's history ("red scares", Cold Wars) and culture (violent crime, tabloid journalism), and points out that
--despite the occasional outburst of emphasis on lie detection (after 9/11, for example), legal and scientific opinions still are split and mostly against it, and
--reliance on the device in any application is almost completely isolated to the US.