IF THE TITLE of "Young Adam," a compelling if singularly sour tale of a young man's moral paralysis, is meant to suggest a character in the biblical creation story, a better allusion might be to the serpent, or at least to something serpent-shaped. Judging by the hyper-sexual behavior of the film's priapic antihero, Joe (Ewan McGregor), a writer-turned-bargeman on the River Clyde in 1950s Scotland, "Young Adam" is the portrait of a male sex organ -- with a man attached to it.

And not much of a man at that.

Oh, Joe gets his share of you-know-what, bedding down with just about every woman he makes eye contact with. There must be some powerful aphrodisiac in the pheromonal effulgence of his coal-dust-caked sweat or some magic in those hard, hungry stares of his. But he's not a man in any other sense, drifting from one animated but coldly clinical sexual encounter to another as if it were the only way he knew to distract himself from the stench of his own rotten conscience.

In this film, which opens with the discovery, by Joe and his employer, Les (Peter Mullan), of a drowned woman's nearly naked corpse floating in the water, sex and death are as intertwined as the limbs of two lovers. It is, in fact, Joe's fanciful description of how the woman might have undressed just before committing, as he imagines it, suicide that he uses to seduce Les's earthy wife, Ella (Tilda Swinton), who owns the barge on which Joe has been hired as a laborer. Later, as the two lie in a post-coital state resembling not bliss but boredom, a fly alights on the nipple of Ella's bare, inert white breast, as though it were a piece of meat. Similarly, a rancid pallor cloaks the film itself, evoking Joe's world in a palette of unremitting, cadaverous grays.

As writer-director David Mackenzie unwinds his unpleasant narrative (based on a book by Scottish Beat Generation writer Alexander Trocchi), jumping from flashback to the present in a way that reveals Joe's hidden connection to the dead woman, we watch as Joe's character passes up one opportunity after another to do the right thing. And I'm not just talking about his obsessive-compulsive coupling. Right after Ella, Joe adds Ella's recently widowed sister and then the wife of his new landlord to his list of bedroom conquests. (Correction: Scratch "bedroom" and replace that with grass, alley wall and pavement. Joe isn't picky.)

What I'm talking about is Joe's unwillingness to come forward and solve what is, at least superficially, the mystery that drives the story of "Young Adam" forward. While some fear-driven inertia is understandable, Joe's utter refusal to accept the consequences of his actions -- or to correct the gross miscarriage of justice that results from them -- is appalling.

In a sense then, "Young Adam" is aptly titled, seeing as it invites us to conclude that Man was debauched even before he bit the apple, that our concern for saving our own skins, at the expense of others', is not something that went wrong with our making, but how we're hard-wired.

It's an especially ugly and pessimistic premise, yet one well worth contemplating, but not for anyone looking for romance or something to lift them out of the muck in which we'll all be sleeping -- at least according to "Young Adam" -- before too long.

YOUNG ADAM (NC-17, 97 minutes) -- Contains nudity, obscenity, physical abuse, images of a corpse and plentiful sex. Area theaters.

Tilda Swinton and Ewan McGregor take part in the cold coupling of "Young Adam."