Margaret

Anna Paquin must have been doing plenty of hand-wringing as Margaret sat on a shelf for years.

After six years of post-production tinkering and reported disputes between filmmaker and distributor, the sophisticated character study that showcases a terrific lead performance from the Oscar-winning actress is finally seeing the darkness of theaters.

Paquin’s work as a troubled teenager dealing with guilt in the aftermath of a Manhattan bus accident is the highlight of the long-awaited sophomore directorial effort from playwright Kenneth Lonergan, whose debut, You Can Count on Me, earned two Oscar nominations following its release in 2000, including one for Lonergan’s screenplay.

His ambitious follow-up is flawed, to be sure, but it’s also witty and provocative, with Lonergan’s sharp-tongued dialogue shining through in the way it intellectually analyzes guilt and contemporary human relationships from a teenage perspective.

Paquin plays Lisa, a precocious and strong-willed student whose relationship with her actress mother, Joan (J. Smith-Cameron), is strained to the extent it generates daily arguments. Lisa’s life takes a turn when she witnesses a bus accident that kills a pedestrian (Allison Janney), in which she might have played a role in the cause.

Lisa becomes consumed by the incident, tracking down the victim’s opinionated best friend (Jeannie Berlin) and confronting the bus driver (Mark Ruffalo) in an effort to reconcile her feelings as she desperately tries to pull her life back together.

There’s a slight degree of self-indulgence at play here for Lonergan, who has a supporting role as Lisa’s estranged father. That means his character in the film is divorced from Joan, who is played by Lonergan’s real-life spouse.

The significant delay in the release date (production took place in 2005) has rendered the film almost as an unintentional period piece, especially in the way it dissects global post-Sept. 11 politics and the Bush administration in high-school classrooms.

At any rate, Margaret features its share of unwieldy melodrama, and the editing room seems to have eaten away at key scenes for some of the supporting performers, including Joan’s opera-loving boyfriend (Jean Reno) and a compassionate teacher (Matt Damon) at Lisa’s school.

What’s left is an uneven, serious-minded, coming-of-age drama with several brilliant character-driven sequences that are both unconventional and emotionally draining. It’s a powerful work that’s certain to generate discussion, and not just for its enigmatic title.

Rated R, 149 minutes.