The movie is an Altmanesque ensemble piece anchored by a major performance by a very game and very brave (and very young) Anna Paquin, who would normally be a shoo-in for an Oscar if "Margaret" wasn't made way back in 2005 and if it hadn't been mired in distracting legal and editing issues. Paquin's Lisa attends a progressive private school whose precocious students are smarter, more probing and verbally quicker than their teachers (who include Matt Damon and Matthew Broderick).
The lynchpin of Lisa's otherwise aimless life is a horrific accident that Lisa causes when she distracts a bus driver (Mark Ruffalo) who promptly mows down a pedestrian (Allison Janney). This brilliantly staged sequence shrewdly juxtaposes the death of one person with the rebirth of another.
Lisa, now no longer adrift, is jolted by bracing, powerful feelings. She's been enlightened and, once one is enlightened, there's no going back. Lisa can't unlearn this harsh lesson and return to her former self.
Lonergan's movie runs two-and-a-half hours (reportedly shortened from the director's three-hour cut by Martin Scorsese and Thelma Schoonmaker) and, frankly, I wanted more. More of Paquin. And more of the cast surrounding her - J. Smith-Cameron and Lonergan himself as her divorced, estranged parents; Jeannie Berlin as a middle-aged woman who becomes Lisa's unlikely new best friend; Jean Reno as a European sophisticate romancing her mom, and Rosemarie DeWitt as Ruffalo's wife.