You think those cowboys in "Brokeback Mountain" have a sexual issue? They are downright mainstream compared to the gender identity of the heroine in "Transamerica."

Peter Kramer, Getty Images Kevin Zegers and Felicity Huffman star in "Transamerica," opening today at the Squirrel Hill Theater only. "Transamerica" Rating: R for sexual content, nudity, language and drug use. Starring: Felicity Huffman, Kevin Zegers. Director: Duncan Tucker. Related coverage Duncan Tucker says 'Transamerica' is ultimately about a family's turning points More movies that have crossed gender lines

She -- formerly he -- is Bree (Felicity Huffman), a transsexual well along in the necessary series of operations and stages of therapy. She's in the home stretch now, saving up for her final "sexual reassignment" surgery in Los Angeles, when she suddenly learns that a rare heterosexual encounter long ago resulted in a son.

That would be Toby (Kevin Zegers), a teenage runaway currently in a New York jail. The bad news is she must go there to bail him out. The worse news is that, once sprung, he wants to (1) find his father and (2) pursue a career in porn films in Los Angeles.

Toby has no idea who she/he/Bree/Daddy is: a man who has become a woman with no particular maternal instincts. Nevertheless, she offers the kid transcontinental transport, secretly intending to dump him at his stepfather's mid-way.

A drama and character study turn into a road movie (the Southwest landscapes are especially nice) and, in between bursts of bonding and mutual discovery, into a semi-comedy as well. The humor is respectful, not campy: Gender dysphoria is full of loneliness, stigmatism and alienation. Director Duncan Tucker wants us to take this bio-psychological anomaly (and Huffman's performance) seriously.

We do, albeit with some difficulty, until Bree decides to make a pit stop (and full confession) at her estranged parents' manse. When these two horrendously over-the-top caricatures (Fionnula Flanagan and Burt Young) are introduced, the careful comedy succumbs to burlesque, undermining Huffman's and Zegers' hard work.

I said I took her performance seriously, not that I liked it. Huffman, an Emmy-winning "Desperate Housewives" star and Golden Globe winner for this role, is very earnest. But it was a strange, risky decision on first-time director Duncan's part to cast a woman to play a man who is becoming a woman. With Huffman, like Mary Martin as Peter Pan or Al Jolson in blackface, the question is not so much how well it's done as why it's being done at all?

Our crossover to bear in "Transamerica" is the constant suspension of disbelief that Felicity is or ever was a male. It's a transmogrification -- rather than a bridge -- too far.