Analyze This and isolated patches of Rocky And Bullwinkle helped establish playwright Kenneth Lonergan's reputation as a clever screenwriter of mainstream comedies, but neither suggested the abilities on display in You Can Count On Me, his debut as a writer-director. Effortlessly blending comedy and drama, the film examines the relationship between adult siblings who, years after their parents' deaths, have pursued different paths. One, Laura Linney, has become a bank employee and protectively raises her son (Rory Culkin), alone, in her childhood home. The other, Mark Ruffalo, has become a drifter who reluctantly travels back to his small hometown after running out of money. Though they come into their reunion with different expectations, the two awkwardly set up house together, re-establishing old ties and reaffirming old conflicts, as Ruffalo bonds (more fraternally than paternally) with the sheltered Culkin and the always-cautious Linney takes up with married boss Matthew Broderick. Remarkably good in films that have underutilized her, here Linney is gifted with a character that makes the most of her twitchy, high-strung persona by pairing her with the agreeably low-key Ruffalo; their personality clashes give the film some of its funniest and best moments. But Lonergan, who gives himself an amusing cameo as a confused priest, has more in mind than laughs. He never hides the scars beneath his protagonists' adopted personas, and he skillfully handles the final act's serious turn. As debuts go, the word "auspicious" doesn't quite do justice to You Can Count On Me, a masterful and moving piece of comic and dramatic understatement. Rarely do movies treat sibling relationships, or any relationships, with the graceful complexity Lonergan manages here. Even it weren't among such slim pickings, it would easily qualify as one of the year's best films.