16 July 2012 | 11:45 am | Ian Barr

It's impossible, and unfair, to talk about Kenneth Lonergan's Margaret, without omitting details of its troubled post-production stage following its 2005 shooting. In brief: Lonergan wasn't allowed final cut, and the unwieldy epic he intended – focusing on a young NYC woman's (Anna Paquin) strained quest for culpability and emotional stability after indirectly causing the death of a woman in a bus accident – became lost in the shaping of a more manageable 2.5-hour theatrical version.

A longer version will eventually surface on home video; for the meantime this cliff-notes version is cause célèbre enough, at the very least for being the kind of dizzyingly ambitious piece of humanist cinema that comes around all too rarely. It's never a smooth ride, willfully placing itself on equal footing with Paquin's Lisa, and bracingly true to her adolescent hysteria and hopeless desire to salvage some kind of reconciliation with the world orbiting her. The cumulative effect of Margaret's many loose ends and frayed edges packs a wallop.