And though not all of Lonergan's conceits work on a scene-by-scene basis (an upper-crust womanizer played by Jean Reno skews a bit too close to caricature), the film has a cumulative power-solidified by a devastating opera-house finale-that's staggering. This is frayed-edges filmmaking at its finest.

It's not a film that's easy to love, but like a song you at first can't stand but then end up humming all day, it works its way past your defenses and curls in close.

It's less successful as a human drama than as a near-Brechtian exercise in what human drama looks and sounds like - a distanced but often car-crash compelling portrait of a teen as an unfinished being.

Lonergan didn't bite off more than he could chew with Margaret - this is his personal moral gymnasium - but he did bite off more than others might want to chew.

Lonergan's dialogue can sweep you up in a whoosh of personality and ideas, but it's hard to see what, apart from ego, convinced him that this story was so epic.