At the opening of Michael Cuesta’s “L.I.E.,” one of the year’s strongest–and riskiest–films, 15-year-old Howie Blitzer (Paul Franklin Dano) is standing on an overpass, looking down on the Long Island Expressway. On the soundtrack we hear him contemplating the many lives the L.I.E. has claimed, including those of singer-songwriter Harry Chapin, director Alan Pakula and, very recently, his own mother. Howie wonders whether it will claim him, too–not in an accident like the others but by suicide.

Thus begins a coming-of-age film that is a boldly imaginative yet subtle exploration of male sexuality in all its contradictions, complexities and fluidity and, beyond that, the interplay of love and sex. By the time it is through, “L.I.E.” has embraced tragedy, folly, perversity and outrageous dark humor. Like “Happiness” and “American Beauty,” it takes an unflinching look at the darker aspects of life in American suburbia.

Howie is the classic bright but seriously neglected kid. His father, Marty (Bruce Altman), is a hotshot contractor who has moved a glamour-girl type into their expensive home only a week after his wife’s death. He’s more concerned with keeping his waistline than with the well-being of his son, who has been devastated by the loss of his mother.

Not surprisingly, Howie’s grades suffer, and he starts hanging out with Gary (Billy Kay), an impoverished kid who’s going to do whatever it takes to get to California, including breaking into houses.

Howie is a virgin, possibly uncertain of his sexual identification but drawn to Gary primarily because he pays attention to him and builds up his self-esteem. In Howie, inexperience and emotional neediness trump his intelligence: He cannot see Gary for the con man he is.

The boys’ break-ins lead to Howie’s becoming ensnared by Big John Harrigan (Brian Cox), a burly, 60-ish silver-haired ex-Marine whose basement is burgled by the boys while Big John is hosting a birthday party upstairs for his ancient, possessive mother. Big John is a big man in his Long Island community. He is also a highly predatory gay pedophile.

Written by Cuesta, a photographer and commercial director, with his longtime friend, writer and novelist Stephen M. Ryder and Cuesta’s brother Gerald, “L.I.E.” deftly depicts how a series of events and a number of lives affect one another, the upshot of which is to bring Big John into a wholly unexpected relationship with Howie. Big John initially looks at Howie, who is an ordinary kid in appearance and demeanor, as he does other boys, with an interest in one thing only.

But Howie surprises him with his ability to speak French, to know a Chagall when he sees one and to recite poetry. As Howie’s life grows ever more precarious, Big John finds the youth bringing out in him loving paternal feelings more than sexual longings.

The filmmakers, in a bold feature debut, dare to humanize a pedophile, but they don’t grant him absolution.

In Cox’s robust yet reflective portrayal, Big John is a tragic figure, but no parent would want him in the neighborhood. His compulsive, practiced pursuit of boys has self-protectively, even reflexively, made him blindly callous to their feelings. Big John has learned to be honest with himself in regard to his sexual desires but remains mired in shame. The filmmakers don’t suggest in any way that the loving feelings that Howie elicits in Big John redeem the older man from his past–and present–predatory ways.

Dano, Kay and Altman all excel in roles that are also highly demanding by any measure, and Marcia DeBonis is most persuasive as a school counselor worried about Howie. “L.I.E” burns with style and energy yet has an effectively contrasting score by Pierre Foldes that is formal and elegiac, underlining the film’s seriousness. (Since the film’s only fairly graphic, briefly glimpsed sex scene involves Marty and his live-in lover, the NC-17 rating not only seems unduly severe but in effect sensationalizes an important theme explored with exceptional clarity and honesty.)

MPAA-rated: NC-17, for some explicit sexual content. Times guidelines: Strong language, strong sexual theme explored in responsible, enlightening manner.