Like a Hamptonite cathedral, the web of endless windows and bleached wooden rafters of John Lee Beatty's imposing set for "A Naked Girl on the Appian Way" could hardly be more light and airy. But Richard Greenberg's old-fashioned boulevard comedy in pseudo-provocative clothing is suffocated at every turn by artificiality.

Like a Hamptonite cathedral, the web of endless windows and bleached wooden rafters of John Lee Beatty’s imposing set for “A Naked Girl on the Appian Way” could hardly be more light and airy. But Richard Greenberg’s old-fashioned boulevard comedy in pseudo-provocative clothing is suffocated at every turn by artificiality. It’s hard to discern the subject of this toothless play about incest that’s not really incest. Maybe the endless capacity of the rich for complacency, denial and rationalization? The functional dysfunction of the happy family? In any case, it seems a flimsy skeleton on which to hang the playwright’s erudite wit.

Playing successful cookbook author Bess Lapin, Jill Clayburgh busily plucks from her kitchen herb garden to prepare a salad of 49 ingredients. But the project is neither completed nor served. The same could be said for Greenberg’s play. With the writer’s usual verbal aplomb, he tosses in one-liners and self-consciously clever observations about the complexities of love, family and relationships. But he neglects to add the fundamental condiment of emotional truth.

In an ambling opening scene that takes too long to engage, Bess and husband Jeffrey (Richard Thomas) trade self-satisfied banter that establishes her as a serene homemaker with a sunny disposition and him as an anxiety-ridden asthmatic. Jeffrey is also a writer, at work on the tome “Business and Art: An Unlikely Interface.” From the studied sophistication of their discourse on semantics, gastronomy and the profound beauty of ignorance as demonstrated by neophyte filmmaker Orson Welles in “Citizen Kane,” it emerges that two of their children are due home after 17 months in Europe.

Enter savvy Juliet (Susan Kelechi Watson) and doltish, adorable Thad (Matthew Morrison), who almost immediately drop the bombshell that they’re in love and plan to marry. Greenberg supplies enough hints early on that the kids are not flesh-and-blood siblings. Even the Playbill cast photos serve as a clue that Bess and Jeffrey have assembled an insalata tricolore of adopted kids in different hues, with Teutonic Thad, Dominican Juliet and Asian Bill (James Yaegashi).

Now that the book on intrafamilial closeness has been rewritten by Woody and Soon-Yi, such a central conflict risks being humdrum — especially since Greenberg has not bothered to set off any real sparks. Unlike in, say, Edward Albee’s “The Goat, or Who Is Sylvia?,” there’s nothing at stake here. Thad and Juliet never really acknowledge the queasiness their situation engenders, and while their parents clearly find the revelation “icky,” their flapping about has an air more of daffy bemusement than of genuine alarm.

Wes Anderson’s movie “The Royal Tenenbaums” dealt with a quasi-incest scenario in the intellectually stimulated environment of a well-heeled, high-cultured family better than this smug sitcom.

The arrival of Yaegashi’s stony-faced Bill in the central act salvages the effort to some extent. Just as gay accountant Mason Marzac was the most memorable character in “Take Me Out” — and the most direct conduit for the playwright’s own voice — so, too, is this outsider the most intriguingly complex figure onstage here.

A bisexual who feels twice rejected by his sister and his sexually boundaryless brother, Bill’s whiny “Why am I never chosen?” outpouring reaches dizzying heights of resentment. Yaegashi’s seething deadpan channels every ounce of bristling animosity in a guy who sees himself as “the runt standing between this chiquita and Rutger Hauer.”

Described by his father as having a “grandiose inferiority complex,” Bill gripes about his librarian job, his second-tier college education, even the preordained destiny of blandness in his name next to the more romantically monikered Thaddeus and Juliet. The unrelenting determination with which Bill paints himself as the victim of low expectations and Asian stereotyping is the play’s most original laugh track.

Beyond that, there’s nowhere much for Greenberg to go. The playwright is soft on his impossibly articulate characters (they casually bandy about terms like phylum, Reichjungen and antinomian), generally declining to challenge them with any real dramatic meat. Bess and Jeffrey, in particular, are too busy congratulating themselves on how evolved and liberal they are to be thrown off-balance by the kids’ revelation.

Greenberg ushers in a contrived third-act twist involving widowed neighbor Elaine (Leslie Ayvazian). And via Elaine’s mother-in-law, the play mines cheap laughs through that reliable old comic standby, the belligerent, trash-talking granny, played to the hammy hilt by Ann Guilbert. Making both these characters also writers of feminism-related tracts extends the playwright’s opportunities for repartee about the minefield of sexuality and interpersonal politics.

In the final scene, Elaine scornfully laments being “caught up in the bourgeois farce of infidelity and divorce.” But while it grazes some interesting points about the construction of false harmonies, “Naked Girl” is actually a bourgeois farce about nothing.

While director Doug Hughes and the tech team do the usual pristine job for a Roundabout mainstage production, the polished execution and lavish design (chez Lapin is like an Architectural Digest porn centerfold) seem to amplify the synthetic quality of Greenberg’s play.

Despite more than capable work from the cast, the most tangible reward is the pleasure of seeing Clayburgh’s warm, wise presence back on a Broadway stage for the first time in two decades.

A Naked Girl on the Appian Way

American Airlines Theater; 740 seats; $81.25 top

Production

A Roundabout Theater Company presentation of a play in one act by Richard Greenberg. Directed by Doug Hughes.

Creative

Set, John Lee Beatty; costumes, Catherine Zuber; lighting, Peter Kaczorowski; original music and sound, David Van Tieghem; production stage manager, Leslie C. Lyter. Opened Oct. 6, 2005. Reviewed Sept. 30. Running time: 1 HOUR, 45 MIN.

Cast

Bess Lapin - Jill Clayburgh Jeffrey Lapin - Richard Thomas Sadie - Ann Guilbert Elaine - Leslie Ayvazian Juliet Lapin - Susan Kelechi Watson Thad Lapin - Matthew Morrison Bill Lapin - James Yaegashi
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