A self-hating, Mexican-American border patrolman secretly infiltrates a group of illegal Mexican immigrants, getting a hard lesson in humility and returning to the nobility of his humble roots in The Gatekeeper, a new film that functions as a self-conscious liberal polemic for immigration reform, with its heart in the right place but its storytelling all over the map.

In an embarrassing and unbelievable early scene, handsome yet stiff Adam Fields (writer and director John Carlos Frey, who may have some of Steve McQueen's tough persona) returns to his childhood home, visiting the family he's ditched out of shame. An ailing, first generation Mexican mother sired him from prostitution. Of course, he's requisitely ashamed and filled with loathing. The emotions in the scene get pushed up to near tele-novella exaggeration, and the ensuing tantrum is indicative of the emotionally simplistic tone of the film.

With the help of a laughably right-wing buddy and radical radio personality (Jack Green), he re-enters Mexico incognito, intending to join a group of illegal aliens crossing the border with a "coyote," secretly wearing a device designed to videotape the entire process and expose the immigration problem to American television audiences (as if no one realizes it's going on anyway).

When the plan goes awry and his American buddies end up dead, he settles down in the "family" of immigrants and lands in a barbaric work camp. Here the contrivances of the film's "investigative" set-up give way to the handful of personal stories so hollow and treacly you'd have to be pretty desperate for a good cry to give yourself over to them.

As Fields finds himself sinking further and further into what amounts to immigrant slave labor and he becomes personally attached (of course) to his fellow workers, the silliness of the events pile up. Everyone Mexican is noble and ready for sainthood, while everyone American is a greedy, sadistic exploiter (and this may well be the case in real life, or at least seem so from the immigrant's perspective). There's no subtlety here, just diametrically opposed stock and cardboard characters - good-hearted peasants and black-hearted exploiters.

I'm frankly surprised that The Gatekeeper has picked up so many audience awards at film festivals around the country, obviously striking a chord in some audiences somewhere, who may feel moved by the film's issue and plight of characters who seem thrown away by the rest of the world, with little or no hope for the future.

But the film itself, issue aside, is executed simplistically and without any real intelligence or dramatic fire, richness or detail. If you're looking for those qualities in a film about immigration, try Gregory Nava's El Norte, John Sayles' Lone Star or Nancy Savoca's stunning new film Dirt, making the rounds on the festival circuit this year.

The most important problem here is that noble intentions do not a good movie make, and first-time director Frey's obvious connection to the subject matter has caused him to lose any edge he might have had in telling an authentic story on a troubling and topical issue.

In attempting to place a sympathetic, human face on the proceedings, he ends up making his film melodramatic, trivial and shallow. As deep an issue as immigration exploitation is, this film is surprisingly inept at giving us any characters that function beyond the most rudimentary and soap-opera-esque dimension.

Everyone in the cast, including Frey himself, functions as a one-dimensional political mouthpiece. The point here is that illegal immigrants are being bought, sold and exploited at deadly costs - and there's no one to protect them because no one sees it's a problem.

There's able support and conviction from the supporting actors playing the Mexican immigrants, including Michelle Agnew as a struggling young mother, Joe Pascual as a hardworking hand who "knows his place," and Anne Betancourt as an older woman who's spent a lifetime of quiet resignation in the camp.

But they can't save The Gatekeeper, heavy with its issue and graceless with its drama, from collapsing into a pushy issue film. The cause is a noble one all right, but the film needs a jolt of real drama, and a little less obvious propaganda.