Felicity Huffman’s Emmy for “Desperate Housewives” might just get some company from a fellow called Oscar if the Academy is ready to look beyond big-studio productions for its best actress nominees this year. In “Transamerica,” a sharp and surprisingly moving road-trip movie from writer-director Duncan Tucker about a parent and child who’ve never known each other finally connecting during an unlikely journey together, Huffman plays a male transsexual, passing as a woman, who’s in the last stages of preparing for a sex-change operation, when she learns through a telephone call from the New York City police that she might have sired a son during her life as a man–a teenager now jailed for hustling. Her counselor (Elizabeth Pena) informs Bree, the former Stanley, that she can’t approve going ahead with the procedure until the matter is resolved, and so Bree travels from California to bail out Toby (Kevin Zegers), who’s been arrested for turning tricks in the city after running away from his southern hometown in the aftermath of his mother’s death. Bree tells him she’s a Christian missionary who regularly helps youngsters in need, and when he informs her of his hope to go to L.A. to find his father (and make a career in porn videos), she offers to drive him there, intending–despite his protests–to drop him off with his stepfather before returning to the West Coast alone.

Of course, things don’t turn out as Bree had planned, and before long the two are continuing to California together. Along the way they meet an assortment of colorful characters, including a free-spirited but larcenous hitchhiker (Grant Monohon) and a courteous Native American good Samaritan named Calvin (Graham Greene), who takes a shine to Bree. The question, of course, is whether Toby will ever find out about Bree’s “condition” and their true relationship. Ultimately they wind up at the Phoenix home of Bree’s estranged mother Elizabeth (Fionnula Flanagan), long-suffering father Murray (Burt Young) and post-rehab sister Sydney (Carrie Preston), where matters reach a crisis point.

It would be easy–and unfair–to pigeon-hole Tucker’s film in terms of the transexual element. Although its tone is very different–a mixture of the humorous and the touching rather than somber tragedy–it’s like “Brokeback Mountain” in that what really distinguishes it isn’t the potentially provocative aspect but its essential humanity. And while movies about journeys of self-discovery and reconciliation aren’t exactly thin on the ground, this one beats the odds. Though the familiarity of the genre stacks the deck against it and the route sometimes journeys perilously close to soap opera, the picture benefits from Tucker’s generally deft writing and affectionate, if sometimes clumsy, direction, and from sensitive and witty acting across the board. Huffman is the anchor of the enterprise, giving a beautifully balanced and nuanced performance, at once drily funny and achingly tender; in her hands Bree is a mesmerizing figure. But she’s not alone. Zegers manages to make Toby’s boyish naivete–one of the least convincing aspects of Tucker’s script, given the boy’s New York life–credible, and conveys a mixture of resentment and vulnerability that complements Huffman’s turn exceptionally well. Greene puts his air of offhanded civility to excellent use, but even more impressive is Flanagan, who’s able to capture both the monstrousness and the underlying sadness of Bree’s mother. And though nothing could moderate Young’s customary pugnaciousness, in this case he gives it a playful quality that gives Murray a charmingly long-suffering feel.

“Transamerica” was obviously made on a modest budget, but it uses its locations well, with both Mark White’s production design and Stephen Kazmierski’s camerawork important contributors to the authentic feel. David Mansfield’s score is a solid plus too.

The most unfair reaction one could have to this picture is to praise it for tackling a “difficult” subject. This is no didactic, Stanley Krameresque piece. The remarkable aspect of “Transamerica,” and of Huffman’s astonishing performance in it, is that by the end you forget how different the characters are from you and realize how much you have in common with them. The film’s triumph is that it’s ultimately much more than a stunt–despite occasional missteps, it’s mostly a sweet, penetrating, funny and intensely human story.