Kenneth Lonergan, who wrote and directed You Can Count on Me, is a playwright, and the lack of music-video experience on his resume is, these days, a welcome relief: Characters talk to one another in this beautiful, compassionate, articulate domestic drama, which won the screenwriting award and shared this year's Grand Jury Prize at Sundance. Actors work together smoothly, drawing from one another more precisely shaped performances than they might otherwise have known they were capable of, and the camera moves unobtrusively in an organically structured plot. In other words, if you're looking for ''American family'' scenes involving red rose petals showered on a naked Lolita, walk on by. Sammy Prescott (Laura Linney) and her brother Terry (Mark Ruffalo), orphaned as children, have found very different ways of adapting to impermanence: She leads a life of habit and overcontrol, raising her 8-year-old son on her own in the upstate New York house in which she grew up. He has pushed away grief by not committing anywhere, to anyone, and strewing mess in his wake. But when Terry drops in to visit Sammy he needs money the unexpected attachment he forms with his nephew rattles his sister so much, she's shaken out of complacency.
You Can Count on Me is so delicate and low-keyed a drama of deep feelings that it hinges all the more crucially on dramatic subtlety. And in that, Lonergan (who, wearing a very different eyeshade, also wrote The Adventures of Rocky and Bullwinkle) can count on a superb cast. In addition to Linney and Ruffalo, players include Matthew Broderick as Sammy's prissy boss and Jon Tenney as her boyfriend. Lonergan himself appears as a priest and, in highly cynical times, creates a thoughtful, serious clergyman in a few lines of dialogue. A