Mack (Psychiatry/Harvard Med.) won a Pulitzer Prize for his life of T.E. Lawrence (A Prince of Our Disorder, 1976); more recently he teamed with Rita S. Rogers for the superb The Alchemy of Survival (1988). Here he tackles a subject that pushes the very boundaries of rational discourse: the case histories of patients who claim to have been abducted by aliens. Mack has been working with abduction ""experiencers"" since early in 1990 and has interviewed over 100 people of various ages and backgrounds, most of whom show no obvious signs of mental illness. The bulk of the book consists of the narratives of 13 subjects told in almost stupefying detail. Their stories have many features in common: the physical descriptions of the aliens (most frequently, short, gray beings with pear-shaped heads and large, dark eyes); intrusive quasi-medical procedures aboard alien ships; and the ""message"" that the aliens are deeply concerned about the future of the Earth. These people are, quite understandably, deeply unsettled by their abductions and often come to Mack for assurance that there is some rational explanation for what has happened to them. Unfortunately, Mack cannot offer them anything beyond assurance that their situation is not unique. He recognizes that, if taken at face value, these accounts call into question basic premises of Western science. Yet as a psychiatrist, he has little choice but to accept that their stories reflect some kind of psychological reality, arguing that strict rationalism needs to make room for his patients' experiences. Abduction leaves the reader with very little solid ground to stand on. In the end, despite Mack's impressive credentials and his sophisticated interpretation of the abduction phenomenon, he leaves a reader still reluctant to discard several centuries of accumulated knowledge in order to accomodate a persuasive psychological -- if not an objective -- truth.