Dan Via's new play "Daddy," which opens on January 31 and, under the auspices of DowntownTheatre Company, plays Wednesdays through Mondays, through February 13, at TBG Arts Center Mainstage Theatre, on West 36th Street, is so au courant that gay marriage, legal and figurative, fuels much of the action, but, in a surprise twist, the plot turns on a taboo, old as the Bible and Greek tragedy, that still turns out to pack a potent wallop. Dan Hilder directs the handsome cast of three and Galway McCullough directs the fights, and the full company's work is very persuasive.

Same sex marriage, the issue, figures prominently into the plot of this intense 95-minute, intermissionless one-act play, in the form of newspaper columns, pro and con, and rallies, attended by the proudly pro and vehemently con, concerning a gay marriage amendment. Extra-legal gay marriage is a no less major theme of "Daddy," as we ask ourselves which two, among the three individuals on stage, represent the couple, as the odds keep shifting. Is it Pittsburgh Post-Gazette journalist Colin McCormack (Gerald McCullouch, of "CSI" fame), and lawyer Stew (playwright Via), old, intimate friends, very involved in each other's lives, who aren't lovers, but perhaps could have been, perhaps should have been? Is it Colin and new young boyfriend Thaddeus Bloom, known as Tee (Bjorn DuPaty), interning at the Gazette, a couple we want to root for? It couldn't possibly be Stew and Tee, at each other's throats as each smolders with possessiveness and resentment over the other's place in Colin's life and home-could it?

Catching Tee in a compromising position-reading Colin's email from his father, containing sensitive financial information-Stew draws on a legal connection to do some probing into Tee's background, and finds out more, much more than he, or we, or certainly Colin bargained for. When Colin is thunderstruck-and the cast plays the revelation scene and its aftermath to the hilt, with McCullouch most grandly devastated-we are equally thunderstruck.

Full disclosure: I downloaded a copy of the play script just before I left home for the theater. Further full disclosure: I didn't read it before I saw the play and, in view of the shocking-shocking!-development, was relieved that I didn't.

Is the plot twist a masterstroke and the play a masterpiece, tugging at our heartstrings? Or, as we notice the soap opera credits in two of the three players' CVs, should we suspect that our emotions are being most masterfully manipulated? If you're a Daddy or a boy, or even if you're not, go see "Daddy" and find out for yourself what the buzz is already about. You won't be sorry. For tickets, at $18, for this thought-provoking play, by turns, funny, furious, sexy, sentimental, and wrenching, visit http://www.SmartTix.com, or call 212/868-4444. All performances are at 8 p.m. and TGB is on the third floor at 312 West 36th Street, between Eighth and Ninth Avenues. For further information, go to http://www.DaddyThePlay.com.