Despite the presence of such powerhouse stars as Dustin Hoffman and Susan Sarandon in the cast, “Moonlight Mile” is really Jake Gyllenhaal’s movie. The young actor, who’s been so impressive in “Donny Darko” and “The Good Girl” recently, plays Joe Nast, the character around whom Brad Silberling’s script revolves. Joe is a withdrawn, perpetually subdued young man who’s suffered a terrible loss–the death, by random violence, of his bride-to-be. Following the funeral Joe remains with his late fiance’s parents, Ben and JoJo Floss (Hoffman and Sarandon), dutifully intending to go into the real estate business with Ben, as had been planned before the tragedy. Essentially he’s going to be the son-in-law they will now never truly have. Of course, the plan–sad as it is–is undone by secrets that each of the three hold, and by Joe’s halting romance with the local postmistress (Ellen Pompeo).

To be honest, Gyllenhaal isn’t a natural for this role. One might expect Joe to be a rather small, mousy sort, and Gyllenhaal doesn’t fit that description. He’s not conventionally handsome, perhaps, but he is attractive, and he has a fairly large frame. He nonetheless tries to convey the necessary vulnerability by working hard to comes across as ungainly. He stoops, affects a perpetually downcast look and shy, hesitant deer-in-the-headlights expression, and moves in a way designed to make him appear soft, uncertain and weak. And Gyllenhaal is such a skilled actor that he very nearly pulls it off–as a technical exercise, his performance is admirable. Unfortunately, the weakness of the material gives one all too many opportunities to notice how studied and artificial his work is.

Nevertheless Gyllenhaal’s performance outshines those of his more formidable co-stars. Hoffman and Sarandon are supposed to play off one another, with the former doing the precise, little-man shtick he’s used before and the latter portraying the sort of sharp, bitter, dominating woman she’s played frequently in the past. But apart from a few scenes in which they capture the raw grief of a couple who’ve lost their only daughter (most of them with Holly Hunter as the woman who’s prosecuting the killer), they never quite seem authentic. Of course Ben and JoJo are supposed to be overcompensating, so the arch, mannered way in which they deal with the ordinary aspects of life was doubtlessly intended as part of the characterizations, but it still doesn’t ring entirely true. Nor do the stars convince as people who have lived together for years.

The upshot is that “Moonlight Mile” never transcends its basically soapoperatic premise in the way that “Ordinary People” or “Terms of Endearment” were thought by many to have done and “In the Bedroom” actually did. That’s rather surprising, given that Silberling based his script on his own experiences as the boyfriend of Rebecca Schaeffer, the young TV star who was murdered by a crazed fan in 1989. (Schaeffer was an only child too, and Silberling spent considerable time with her grieving parents in the aftermath of her death.) However heartfelt the writer-director’s motives might be, however, in fictionalizing the story through which he lived he’s cheapened it by resorting to such hokey devices that even a fine cast can’t rehabilitate completely. Silberling’s script unfolds as an uneasy mixture of contrived domestic drama and half-hearted humor rather than a serious portrait of the devastation and anger that family and friends must feel at the sudden loss of a loved one. Certainly the romance that Silberling has contrived between Gyllenhaal and Pompeo doesn’t help, composed as it is of a series of overly “cute” incidents; and the “secret” that Nast keeps from Ben and JoJo has an unfortunate air of melodramatic desperation about it. The nobility of Silberling’s intentions is undercut by his failure in execution.

So “Moonlight Mile” crosses the finish line as one of those “what might have been” films that will be remembered more for its potential than for what it actually delivers. But despite its flaws, the film does at least showcase Gyllenhaal, who’s quickly emerging as one of the most striking and talented young actors working today.