There have been quite a few films about the grief felt by parents over the loss of a child, some of them extraordinarily fine—“In the Bedroom” and “The Sweet Hereafter” are two that come to mind. But Shawn Ku’s film adds guilt to the grief, by portraying the traumatic effect on suburban couple Kate and Bill Carroll (Maria Bello and Michael Sheen) when their troubled son Sam (Kyle Gallner) goes on a shooting spree on his college campus before taking his own life.

Much of the trauma comes, of course, from the couple’s feelings of shock over what their son has done; they castigate themselves for a failure to see the torment the boy was going through, rehearsing their own failings in raising and nurturing him as causes behind his act. And in the process their marriage frays and collapses, along with the job to which Bill’s devoted so much of his time and effort, as the two increasingly blame one another for what happened and become more and more estranged. Eventually, in fact, they’ll separate.

But the film also portrays the reaction of outsiders toward the Carrolls, the crush of news media insistent on probing into their grief and of people who hold them responsible, at least in part, for their son’s crime. The pressure quickly compels them to abandon their home, first to move in which Kate’s brother Eric (Alan Tudyk) and his wife Trish (Moon Bloodgood)—an arrangement that itself becomes untenable when Kate ruffles her sister-in-law’s feathers by taking over the house, including Trish’s maternal duties—and then into a motel presided over by a kindly clerk (Meat Loaf Aday). But the dissolution of their marriage continues inexorably, though Kate, who returns home, appears to find a sympathetic ear in a young author (Austin Nichols) whose manuscript she agrees to edit, as well as commiseration from a neighbor.

“Beautiful Boy” is at heart a two-character drama, and Bello and Sheen powerfully convey Kate and Bill’s astonishment, pain and anger. But the supporting cast make smaller but telling contributions. Sam may be little more than the catalyst to the story, and his torment in expressed in only the most fragmentary, elliptical fashion, through a single phone conversation, brief clips from his rambling video testament, and recollections by others. But Gallner uses his few moments to etch a searing glimpse of a troubled, morose young man whose desperate need of help goes unanswered. Tudyk is nicely restrained, as (more surprisingly, perhaps) is Aday, and Bloodgood is good enough to make you empathize with a character that might have come off as totally unlikable. Visually the picture isn’t much more than utilitarian, but the starkness suits the subject.

“Beautiful Boy” could easily have become a Lifetime-type movie, filled with the most obvious melodramatics and simplistic answers. That it largely avoids such pitfalls is a tribute to the cast, to Ku’s sensitive direction, and to the satisfyingly enigmatic script he’s fashioned with Michael Armbruster. This isn’t an easy film to watch, but while a wrenching experience it’s also a rewarding one.