“Every parent’s nightmare” would be the evening news boilerplate description of “We Need to Talk About Kevin,” Lynne Ramsay’s disturbing movie about the mother of a child who goes on a killing spree at his high school. That trite phrase is accurate in an almost technical sense: Ms. Ramsay (who adapted Lionel Shriver’s novel with Rory Stewart Kinnear) follows a kind of dream logic in telling a chronologically splintered story, weaving patterns of associated images and sensations into an intense and claustrophobic web of fear.

But the vividness of its effects makes the film very much a particular parent’s nightmare, pitched at the extreme boundary of everyday anxieties. Tilda Swinton, who plays the anguished mother, is far too specific a screen presence to be an easy audience surrogate. Much of the queasy fascination that the film exerts is the result of her uncanny ability to play against any imaginable type.

Her character, Eva Khatchadourian, is too complicated for pity, projecting a mixture of cold poise and extreme vulnerability that makes her predicament especially awful. We watch as she loses everything except her dignity, but it is precisely that noble, steely pride that places her just beyond the range of a sympathy that she would most likely refuse, in any case. Video: An excerpt from a TimesTalks interview with Tilda Swinton

“We Need to Talk About Kevin,” though it evokes real-life atrocities like the 1999 Columbine school shootings, is less a psychological or sociological case study than a horror movie, a variant on the bad-seed narrative that feeds on a primal (and seldom acknowledged) fear of children. What if they turn out wrong? What if we can’t love them? What if they refuse to love us? These worries are rarely dealt with in the child-rearing manuals, but they hover over modern nurseries like the ghosts of ancient fairy-tale curses.