BETRAYED * * * 1/2 Debra Winger, Tom Berenger, John Heard; rated R (violence, sex, partial nudity, profanity, vulgarity); Century Complex, Cineplex Odeon Holladay Center Cinemas, Cineplex Odeon Trolley Square Cinemas, Mann 6 Plaza Theaters.

"Betrayed" is shocking, frightening and, apparently, based on factual incidents. It is somewhat exaggerated for cinematic purposes, but even with its stretches there is enough scary material here to raise the hair on your neck and maybe even cause you to question your own attitudes toward racial discrimination.This is a film by Costa-Gavras, the Greek director best known in this country for the Jack Lemmon-Sissy Spacek political thriller "Missing" a few years back, and with "Betrayed" he has again pulled out complex performances from his stars and built suspense in a very timely tale.

"Betrayed" begins with an incident patterned after the murder of Denver "shock radio" deejay Alan Berg a few years ago. In the movie the setting is Chicago, where an "insult" radio personality (played by the wonderful character actor Richard Libertini) is gunned down by white supremacists armed with MAC 10 machine pistols in an underground parking lot.

The film then abruptly shifts to serene farm fields somewhere in the Midwest, where we meet combine operator Debra Winger, who is being romanced by local widower Tom Berenger, the proud papa of two bright young children.

He's a Vietnam War hero and a pillar of the community, though a few of his neighbors for some reason shun him. That is the first puzzling clue to Winger that something is amiss.

But then we find that Winger herself is not who she seems. She is in fact an undercover FBI agent infiltrating a community that reputedly has ties to the white supremacist group suspected of killing the Chicago deejay.

As she gets to know these Middle America folks, however, she becomes convinced she's on a wild goose chase and tells her bosses as much. She also falls in love with Berenger and his family as they welcome her with open arms.

But after she and Berenger consummate their relationship, he takes her with him on "the hunt," with MAC 10 machine pistols in tow, a sequence that is at once a repulsive catharsis for Winger's character and the film's most shocking moment, the antithesis of the calm tone up to that point.

After that the film could have just slowly drifted downhill, since it's pretty hard to top this shocking moment, but Costa-Gavras opts to slowly rebuild suspense as Winger gets deeper and deeper into the movement and Berenger comes to trust her more and more. And though "Betrayed" occasionally threatens to become just another labored cop (Fed) thriller, there is much more meat here, resulting in a number of terrifying plot developments that build until the film's tragic climax.

One of the odd choices made by the director and his screenwriter, Joe Eszterhas ("Jagged Edge"), is to make the FBI agents who are Winger's superiors as questionable in their moral thinking as the members of the white supremacist group. In their own way they are as racist and have just as little concern for the value of human life as the film's more obvious villains.

Are they saying we are all racists to some degree and should, each and every one of us, reassess ourselves? That is open to interpretation, but one thing's for sure - you will leave this film feeling moved and disturbed and talking about it.

And how many truly thought-provoking films are there these days?

"Betrayed" is rated R for violence, some brief sex and nudity, profanity and vulgarity.