Writer-director Lonergan's 2000 debut You Can Count On Me, a low-budget indie drama about the fractious relationship between adult siblings was a revelation and one of the best films of its genre and year.
His follow-up has been a long time coming: it was shot seven years ago with a dream cast (small roles are taken by Kieran Culkin and Matthew Broderick) and heavyweight producers (two of whom, Anthony Minghella and Sydney Pollack, died in 2008).
But it became mired in legal suits and counter-suits, mainly because Lonergan wanted a three-hour cut and the studio wanted a two-hour one.
The result, which splits the difference, is not the version Martin Scorsese hailed as a masterpiece in 2006, though since Scorsese was instrumental in finessing the eventual (and commercially catastrophic) release, he was presumably happy with the finished product.
It's hard to share that unbridled enthusiasm: Margaret is too long, by at least half an hour, in part because it has one too many subplots and - to compare it to a fugue - it revisits its principal subject too often, to too little effect.