Writer-director Courtney Hunt developed Frozen River from her short of the same title and saw this first feature go on to triumph at a number of film festivals including Sundance. And no wonder. This is a gripping, beautifully written drama suffused with authenticity, thanks largely to the outstanding performances and well-chosen locations near the New York/Canadian border. And with the mounting flow of illegals into this country and the growing economic challenges spreading to new demographics, Frozen River can also boast a certain timeliness.

The film tells the all-too-convincing story of struggling trailer mom Ray (Melissa Leo), who works part-time at a one-stop to support her 15-year-old son T.J. (Charlie McDermott) and his younger brother Ricky (James Reilly). There’s precious little money because Ray’s gambling husband has gone AWOL with the down payment for the new trailer they need. And T.J., a victim of the broken marriage and the dire financial situation, is a troubled teen required to assume household responsibilities usually left to parents.

The rural, colorless border area where the family resides and where jobs are scarce is no help to their problems until Ray meets Lila (Misty Upham), a single Mohawk mom on the nearby Indian reservation who has plans to smuggle illegals to get money so she can reclaim her baby son. Their first encounter is not auspicious, as Ray has to chase down Lila after the Mohawk tries to steal her car. When Ray learns why Lila needs the car and understands her circumstances, the two bond.

Together, they use Ray’s car to make their runs across the reservation and border to smuggle in Asians. The jobs are fraught with drama—one run includes the possible death of a couple’s baby. But Ray and Lila become so successful, they are able to embark on what they believe will be their final run across the frozen St. Lawrence River. Of course, spoilers are due: Encounters with the vicious, corrupt Jacques (Mark Boone Junior), the Quebecois smuggler in Canada, and law-enforcement officers closing in on both sides suggest their misadventures are not over.

It’s certainly to filmmaker Courtney Hunt’s credit that she has us rooting so vehemently for her distaff “criminals.” And kudos are also due for the superb cast, especially leads Leo and the also remarkable Upham.

Hard-working Leo, a vet of so many indies, finally gets the material she deserves and she owns it. If there’s any justice, her performance will not be forgotten when awards season rolls around. McDermott convinces as the rebellious, damaged older son, and Michael O’Keefe is pleasing as a state trooper we hope might come to Ray’s rescue.

Like The Visitor, this is emotionally packed dramatic indie work at its best. But lacking the colorful urban setting and intermittent hipness that enriched the more upbeat Tom McCarthy work, the pervasively grey Frozen River is at risk for a colder box-office reception. But its grasp of time, place and state of mind and economy is firm and unforgettable.