Of ambiguous morality, the antihero Joe looks back to another Joe, surnamed Lampton, of Angry Young Man John Braine's (and Laurence Harvey's) Room at the Top and Life at the Top. Serendipitously, the permanently named river Clyde recalls Clyde Griffiths of Dreiser's An American Ttragedy, who became Montgomery Clift in A Place in the Sun. At one time Britain's and America's literary hopes and their despairs, both novelists are in eclipse -- though our Terre Haute son is currently being revived -- but their two protagonists do bear on the film Young Adam. Social climbers both, they aspire to the top, in the process the Brit losing what soul he possesses, the American his liberty and life.

In and around 1950s Glasgow, when it was reputedly Europe's most rough-and-tumble port city, Scottish director-writer David Mackenzie's sensual observant Joe (Ewan McGregor) is a drifting but hardly innocent pre-apple Adam. Its ironic title from the novel by the late Alexander Trocchi -- once decried in Edinburgh as "cosmopolitan scum" -- the film opens with credits set against river-bottom rubbish, then narrows upwards onto a floating corpse. Working for and living with houseboat-bargeman Les Gault (Peter Mullan), Joe notices the body and, after the two men hook it ashore and notify authorities, tenderly touches the dead woman's back and arranges a petticoat to cover the buttocks.

Casually sensual and yet sad, he imagines for Les and his scoldy wife Ella (Tilda Swinton) the young woman's end, a deliberate disrobing prior to jumping from a bridge. There in the cramped belowdecks quarters, as the father is absorbed in his newspaper and the child his comic book, Joe fondles Ella beneath the table and will soon seduce the frumpy, unhappy wife. The story, in fact, is one long series of such sexual encounters, with, in fairness, the drifter not necessarily always the aggressor.

Through a series of short flashbacks in his mind, surfaces of the past are revealed. Joe's personal background, however, remains undisclosed, fittingly so, since he is complete, or incomplete, unto himself. Quiet and handsome, he is equally sexual predator and prey, a man running from commitment but a human mixture who saves Ella and Les's son Jim (Jack McElhone) from being crushed or drowned by a canalboat yet can "spend all day wanting to kick [the kid] overboard."

His smile charming, his relationships tender and simultaneously brutal, he finds fair game any and all females. While the media and tavern talk build up the case of the two-months' pregnant drowned woman, Cathie Dimley (Emily Mortimer), as sexually motivated murder, Joe softly says he knows it to have been an accident, instead. Amidst the flashbacks, we learn of Cathie's ties with Joe, then an aspiring socially conscious writer. As underlined by a scene in which custard and condiments replace Brando's Last Tango butter, theirs was a union of hungry pain and pleasure.

Two other such past scenes, emphasizing the girl's helpless fear of water, are out of Dreiser's adumbrations with Roberta Alden, whose death by water will also be Cathie's. Joe disposes of his lover's clothing -- though why the ominous close-up of her overlooked flannel shirt? -- and believes that her arrested semi-boyfriend Daniel (Ewan Stewart), a married father of four, will be released. Still waters in this case do not run deep, for Joe is not self-analytical, he simply moves on. Though society's conscience condemns a person like him, he, too, is helpless -- he would have saved the woman if he could have, he would free her condemned plumber friend if there were a way, but all is too circumstantial, too late by a second or a month.

This is a work of mood rather than the moral -- as opposed to moralistic -- tale that some may think it should have been. Naturalistic in method, fatalistic in implication, it makes good use of the impersonal water and rocky beach, the grime, pubs, cold-water flats and unique Glaswegian accent -- toned down but still unintelligible in spots -- to convey a view of life as it was, and is. Reinforced by a broody David Byrne score (plus Mingus' "Haitian Fight Song"), the effect is sharply observed, and depressing. Justice does not exist, life struggles and is often unhappy, some survive unbroken or at least alive, and some do not, willy-nilly.

(Released by Sony Pictures Classics and rated "NC-17.")