A house on a truck keeps pulling up to a falling-down trailer, but then it is driven away. The house is supposed to replace the trailer, but the tough single mother who ordered it and said she'd pay up can't. So the house keeps leaving again. It's a tormenting repetition that echoes the other tormenting repetition in Courtney Hunt's indelible first feature film: the aging, resolute white mother and a young, widowed Mohawk woman driving back and forth across a frozen river with equally determined, desperate people stuffed in the trunk.

Frozen River was shot in subzero weather on Lake Champlain in northern New York, and it renders starkly the cracking lives of two women, Ray (the mother, played by the truly great Melissa Leo, whose face you'll recognize from a hundred nuanced supporting roles), and Lila (Misty Upham). These two aren't friends by a long shot. They meet when Lila tries to steal Ray's car, which is the only thing Ray's no-count gambling husband left behind when he split. But both women live in the banal peril of poverty, and they happen to be separated from the Canadian border only by a largely unpoliced river. Human trafficking pays.

Depending on who's in the trunk, it's also charged with various brands of post-9/11 ethnic tension. Ray sometimes exorcises her guilt cruelly on her passengers. Hunt's refusal to be sentimental about her complex characters' tribulations and misdeeds is what's so shocking and refreshing about this movie. After two crescendoing climaxes—one midnight trip that almost goes terribly wrong, and another that pits the women against each other yet again—the ending feels a little neat. But when you walk out of the theater, you hardly remember how it ended. You just notice yourself thawing out, gratefully.