Thirty years ago ... began one of the longest, most expensive and notorious criminal investigations in American history. A Los Angeles grand jury charged Raymond Buckey, a 25-year-old teacher at the [McMartin] preschool, and six others with 321 counts of sexual abuse involving 48 children. In the end, after seven years and $15 million, the case fell of its own weight, ending without a single conviction. McMartin was the first of a series of prosecutions in the 1980s that have come to be seen as a collective witch hunt, in which panicked parents and incompetent investigators led children to make up stories of abuse by adults at day care centers and preschools. But what if the skeptics went too far? What if some of the children were really abused? And what if the legacy of these cases is a disturbing tendency to disbelieve children who say they are being molested? Those are the questions that frame The Witch-Hunt Narrative, [a] new book by Ross E. Cheit, a political scientist at Brown University who spent nearly 15 years on research, poring over old trial transcripts and interview tapes. His conclusion about the McMartin case is that the outcome was "doubly unjust." While he acknowledges that some defendants were falsely accused, he argues that Mr. Buckey was probably guilty, meaning that some of the children were not only sexually abused but "have been demeaned by the witch-hunt narrative's assertion that the entire case was a 'hoax.' " He thinks the continued treatment of these cases as a modern-day episode of mass hysteria does disservice to children and even puts them in danger.