Meanwhile, the social workers, therapists and law enforcement agents who worked on the McMartin case and others were consulted by colleagues throughout the country. In February 1985, Kenneth Lanning, an F.B.I. agent, held a four-day seminar titled “Day Care Center and Satanic Cult Sexual Exploitation of Children,” attended by police officers, lawyers, social workers and academics from across the country. One pamphlet told investigators to look for signs of cultic abuse including “candles” and “jewelry.” One handout listed 400 “occult organizations,” rather loosely defined: a collective of feminist astrologers in Minnesota made the list.

Why were so many police officials and parents willing, even eager, to believe that such abuse was widespread? Other authors have put forward theories. Lawrence Wright, in “Remembering Satan” (1994), focused on fundamentalist Christianity’s fear of a literal Satan stalking the earth. Elaine Showalter, in “Hystories” (1997), showed how the psychological establishment, and feminists within it, intrigued by trauma theory, so-called multiple personalities and a new belief in recovered memories, was primed to believe outlandish stories of abuse, especially from women. Believing the victim became nonnegotiable — with adult female patients, then with children and even toddlers.

Mr. Beck, an editor of the literary magazine n+1, places such accounts in the context of right-wing resurgence in the 1980s. Feminists had insisted that not all was well with the nuclear family, which they said was a site of patriarchal repression. Anti-feminists, evangelical Christians and law-and-order advocates conveniently refocused attention on the children, away from the grievances of grown women. In this right-wing narrative, what was wrong with the family could be blamed on mothers who had joined the work force and dumped their children in day care centers, where Satanists paid them the attention that their mommies wouldn’t.

Feminists had been early advocates for abused children, but it wasn’t their primary focus. “In the 1970s feminists had talked much more about rape than about child abuse,” Mr. Beck writes. But by 1980 or so, legislators no longer wanted to hear about the role of race and class in sexual violence. “What legislators and pundits were still willing to hear, to the exclusion of almost everything else on the feminist agenda, was that the country’s children were at risk.” Mr. Beck believes that an unholy alliance between anti-pornography feminists, like Andrea Dworkin, and the Christian right fostered the overly fearful climate in which schoolchildren were lectured about “good touch” versus “bad touch,” and adults could be easily accused of the latter.

At times, Mr. Beck loses focus. The multiple-personality fascination and recovered-memory therapy — both now on the fringes of psychology — belong in the same book as, say, the doctor in the McMartin case who thought that the anus of an abused child would open, or “wink,” when swabbed; they’re features of the same collective, paranoid fantasy. But layered on top of straightforward case narratives from Manhattan Beach, Olympia, Wash., and Long Island (the case made famous in the documentary “Capturing the Friedmans”), they make for a crowded book, one that could have used better traffic direction.