But instead of going back to New York - ''where everything is efficient and functioning, the absolute opposite of Louisiana'' - he found a room in Homer, a coastal town south of New Orleans, and hung around the fishing docks and bars. The script he wrote there became Beasts of the Southern Wild, a fable of survival set in a half-imaginary, largely feral community beyond the broken levee; it is based on a play by Lucy Alibar but, in adaptation, owes at least as much to Zeitlin's experience. ''Writing is as much about going to strange bars I've never been to before as it is about sitting in front of a typewriter,'' he says.

This, finally, is his explanation. What it means to belong in a place - and the powerful draw of this place in particular - is inscribed in every frame of this film that won the Camera D'or at Cannes and the Grand Jury Prize at Sundance. Most of the actors are people Zeitlin met in bars or while working on Glory at Sea; Dwight Henry, who plays the film's tragic anti-hero Wink - a dying, drunken swamp-dweller - ran the local bakery. Wink's daughter Hushpuppy (Quvenzhane Wallis), a grave and dignified child who provides the film's eyes, ears and narrative imagination, was chosen from open auditions of more than 3500 girls. She was five years old at the time. ''I never thought we could get a performance like that out of someone that young,'' Zeitlin says. ''I just would not have believed it.

''The role was written more like a comedy, in a sillier, playful, cute way, which is really hard to imagine now. But once she came in, it was clear we didn't have to skirt around the emotional core of the film.''

Wink's parenting would not survive any kind of scrutiny from social welfare; nor would Hushpuppy's occasional schooling with the local herbal ''treater''. But ''the Bathtub'' - the bay where they live - is way beyond the reach of officials. Zeitlin wanted to tell the story from a child's point of view, he says, because her loyalties are clear and uncomplicated.

''There is a clarity of emotion at that age,'' Zeitlin says. ''There is that initial question: why would you stay here? From the point of view of a child, it doesn't matter how horrible a parent you have: tell any six-year-old they should leave and they won't listen, because there is a biological connection that shouldn't be questioned. I thought that connection and that clarity of emotion … towards her father would unlock the answer to that question. It comes down to something in your gut.''

Zeitlin can talk cogently about the loss of land due to salination, the destruction of marshlands by oil pipelines and other real issues with political solutions. There is probably a great film to be made, he says, about the ''very good people'' agitating to dredge mud from the river and rebuild the land that used to protect the fringes of the bayou from the sea. But he didn't want to make that film. Beasts of the Southern Wild is about a mythical place where the Cajun music of western Louisiana and the food of the east and the carnivals of New Orleans are muddled into ''a kind of gumbo''. Even more fancifully, the bordello where Hushpuppy pictures her runaway mother looks like something from 19th-century photographs of the Big Easy: all corsets, cabaret and Southern Comfort.

For a child in Homer, he explains, New Orleans is ''this distant city with an aura about it. So if you heard your mom had gone away, you might imagine that's where she ended up. But I wanted to keep everything within the bounds of plausibility.''

For Hushpuppy, everything is plausible; the monsters she sees emerging from the bayou mist are as real as crawfish. ''We thought a lot about when it was her imagination, what's real and what's fantasy,'' Zeitlin says. ''And eventually I just started thinking about being six, and remembering that there weren't those two worlds then. It was just one world, and it was filled with things adults thought weren't real.''

When he first arrived in Louisiana, he remembers, it seemed magical and mythical to him, too. He doesn't name the hurricane that ravages the Bathtub in his story; Katrina, he points out, was one of a string of such storms. ''There was a feeling that this was going to be constant, that life in Louisiana was going to be storm life. So, to me, it felt less like an interpretation of a current event and more like we were entering this age of an almost Biblical apocalypse, with the waters rising and the fish dying and the trees dying.''

He was also trying to escape the political positions that have hardened around Katrina. ''I wanted to step away from that and make something that felt like a folk tale that could be engaged with around any campfire, be it of evangelical Christians or leftist hippies. I was imagining you could have people who grew up in this part of Louisiana telling their children there was this beautiful place they had, but it didn't exist any more. The extinction of a culture shouldn't be a tragedy that gets sliced up by Democrat and Republican.''

Beasts of the Southern Wild screens Wednesday 9pm at the Forum Theatre and on August 10, 6.30pm, at the Greater Union, for the Melbourne International Film Festival, miff.com.au. It opens nationally on September 13.