"The American Plan" is a peculiar little play that attempts to explore the underside of our impulses in a world beyond our control. Playwright Richard Greenberg, who's known for coating his works with an intellectual gloss, certainly delivers on that front. And yet despite some fine performances, in the end "The American Plan" fails to live up to its intriguing premise.

In 1960, characters Lili Adler and her mother Eva are engaged in their own "cold war" of sorts. Lili is a very bright, emotionally fragile young woman. Eva, a German Jewish refugee with a superior attitude, is domineering.

Their housekeeper, Olivia, is a cultured black woman who, as Lili puts it, "endures." With a hefty inheritance from Lili's late father, they spend the summer months in a Catskills cottage across the lake from the famed resorts. They are outsiders in this place, which is just the way Eva prefers it.

But one day, a handsome young gentile arrives on the scene and Lili is smitten. He, in turn, falls for her, and for a while "The American Plan" is a conventional romance.

But then the plot thickens. A mysterious man shows up late in the action, the lovers' plans go awry and the viewers are left scratching their heads. Is Eva a monster or a protector? Does Lili turn into her mother?

And what is "The American Plan" anyway? To conceal our true selves, marry rich and live happily ever after?

It's fine to raise questions, but Greenberg's script is too ambiguous for its own good. The characters, who sound more like mouthpieces for the author, ring false.

The performances, however - the two leads in particular - couldn't be more honest. Lily Rabe is once again acing a difficult role, turning the hyper-intelligent Lili into an endearing neurotic, and Mercedes Ruehl is simply astonishing, using impeccable technique to make the intimidating, old world Eva all too real. You can practically smell her overpowering perfume.

Theatergoers may find parallels between "The American Plan" and other better-known works. "The Heiress," based on a Henry James novel and Tennessee Williams's "The Glass Menagerie" come to mind. But compared to these great American plays, "The American Plan," smart as it is, does not come close.