Jessica Stern is among the world’s experts on violence and evil, a woman who spends her time thinking about bad men and bad deeds. She has lectured at Harvard about terrorism and is the author of a respected book, “Terror in the Name of God: Why Religious Militants Kill” (2003). During the Clinton administration she was on the staff of the National Security Council. She presents herself as hard, no-nonsense, buttoned up. She is certainly possessed of the perfect surname. “If the plane goes down,” she writes in “Denial,” her new memoir, “you want me at the controls.”

“Denial” is Ms. Stern’s plainspoken and very raw account of why, long before 9/11, she was driven to study terrorism and to put herself repeatedly into danger as she flew around the world, like some scholarly twin of the former CNN war correspondent Christiane Amanpour, interviewing committed terrorists. Central among the reasons, it turns out, was her own experience of terror. On Oct. 1, 1973, when Ms. Stern was 15 and her sister 14, the two of them, alone in a suburban house in leafy Concord, Mass., were raped by a man who cut the house’s telephone lines before walking inside and leading them upstairs.

Ms. Stern describes that evening in brutal detail. It was a night that changed her and taught her a dire lesson: “Shame can be sexually transmitted.” The crime wasn’t properly investigated. The police didn’t believe her when she said the rapist was a stranger. Because her story and those of others were not publicized or taken seriously enough by the police, the same man was able to rape some 44 girls — an incredible, heart-collapsing number — from 1971 to 1973. “The entire community,” she writes, “was in denial.”

About these facts Ms. Stern is understandably bitter. Her pain is amplified by other sinister aspects of her upbringing. There was the grandfather who took naked showers with her and may have molested her. This same grandfather, a doctor, thought X-ray machines had curative powers and accidentally killed Ms. Stern’s mother, who he believed had an enlarged thymus. She died at 28 from lymphoma caused by an overdose of radiation; the author, at the time, was 3. Ms. Stern’s father, who had twice remarried, did not care enough, upon learning that his daughters had been raped, to return immediately from a trip abroad. This was a family with issues — issues that, like the sun, were stared at only glancingly.