The most compelling movie suspense thrillers I've ever seen were Henri-Georges Clouzot's "The Wages of Fear" and Andrzej Wajda's "Kanal." Both are fatalistic masterpieces: profoundly harrowing accounts of characters trapped in situations that doom them despite inspiring acts of heroism.

I thought nothing could surpass the teeth-grinding tension achieved by Clouzot until descending into the sewers of Warsaw with Wajda's battered Resistance fighters. So I naturally looked forward to the Wajda feature, "Man of Marble," included in the series of recent Polish films being premiered at American University for the next week.

Wajda has made more than 20 features in a directing career that began in 1955 with "A Generation," the first of a war trilogy completed by "Kanal" and "Ashes and Diamonds," made four years ago. "Man of Marble" is a biographical mystery story whose structure recalls "Citizen Kane." It will be shown tonight at 7:30 in the New Lecture Hall at American University.

Wajda hasn't ceased to be a substantial, inventive modern filmmaker. Although it's in the nature of an engrossing disappointment, "Man of Marble" suggests that his body of work, rooted in a culture and political system as remote from our own as the Bengal of Satyajit Ray, may turn out to be equally impressive, pertinent and durable.

"Man of Marble" is about an aspiring, high-strung young filmmaker, vividly embodied by Krystyna Janda, who hopes to satisfy her film school thesis requirements with a documentary on the life of a forgotten proletarian hero. In the postwar period the communist regime had extolled her subject, a peasant-turned-bricklayer named Mateusz Birkut, as a paragon of hard-working, patriotic virtue. Later he fell out of favor and receded into obscurity. The curious filmmaker wants to discover whatever became of Birkut.

It's a fascinating search, documented by the impressions of people who knew him and by miscellaneous film evidence, notably a wittily recreated and then unmasked propaganda short called "Architects of Our Happiness." Despite the image-making nonsense, Birkut happened to be the real article: a sincere, strong-backed common man of great industry and integrity. The full extent of his naive decency is revealed only after he's betrayed and ostracized.

After nearly three hours of absorbing biographical detective work, it's deflating to discover that Wajda himself seems to be lacking a few key pieces to the jigsaw puzzle. The movie remains awkwardly open-ended. Wajda evidently abandoned a concluding recollection of Birkut by his son, the final witness located by the filmmaker, and perhaps this discarded sequence would have completed the story in the way it seems to require. We may not lack any essential information about The Forgotten Man, but the movie does need some form of summation, if only a rhetorical kicker like the incineration of Rosebud in "Citizen Kane." Wajda's film seems to cave in at the fadeout for want of a Rosebud to go up in smoke.