Rosalind Chao and BD Wong Photo by Ahron R. Foster

The Atlantic Theater Company's intimate black box space, located a few blocks south of its mainstage home, is the perfect venue to focus on the kinship between a sister, here called "Q," and her younger brother, "Z," whose lives, despite an upbringing mostly under the same roof, set them spinning in separate directions. What gives the play its special fillip is the fact that Q, seven years older than her brother, was born in an unspecified "Old Country" and is, along with their parents, an immigrant. On the other hand, Z was raised in "This Country" (locale also unspecified) and has little connection to the places and people who are etched in Q's earliest memories.

In its structure, What Became of Us may remind you of A. R. Gurney's Love Letters, in which a lifetime of correspondence between a man and a woman is read aloud to us in alternating monologues. Here, however, the back-and-forth takes the form of an ongoing conversation of many years' duration. Sometimes, the characters speak to one another; at other times, their words are directed at us.

If I haven't yet identified the actors portraying Q and Z, it's because What Became of Us employs another tactic that is a hallmark of productions of Love Letters, the use of alternating casts. That's the reason the characters do not have specific names, just as it is the reason for referring to "The Old Country" and "This Country." The playwright stipulates only that the actors playing Q and Z be of the "same diasporic background," which means, in effect, that the audience is likely to fill in the blanks based on perceived characteristics of the performers. In essence, and however non-judgmental we think we are being, stereotyping and corresponding assumptions are expected to be supplied by us.

For this production, there are two casts. The first pair, at the performances to which critics were invited, are Rosalind Chao as Q and BD Wong as Z. Shohreh Aghdashloo and Tony Shalhoub will pick up the roles later in the month, with both sets of actors performing in succession or back-to-back for a few "double-feature" events. Gimmicky marketing, no doubt, but undeniably intriguing, and those seeing it with Aghdashloo and Shalhoub will bring different preconceptions to the table.

With Chao and Wong, American actors of Asian family backgrounds, it's not difficult to imagine switching out "Old Country" for China and "This Country" for the U. S. And, especially when Q talks about what it was like for her being an only child for her first seven years, and of having her feet planted in both worlds, it may remind you of the stories that novelist Amy Tan ("The Joy Luck Club") relates, of serving as the go-between for her mother in day-to-day dealings with English speakers and American customs. Meanwhile, when Z comes along, he is, for all intent, raised to be an American boy, with all of the freedoms and risks that entails. And later in the play, when he refers to his own son as the "Golden Child," it's not hard to imagine that he, too, was his parents' "Golden Child."

The entirety of the 75-minute play, directed ever so gently by Jennifer Chang, deals with Q and Z's lives in common and in contrast as shaped by their experiences, upbringing, and expectations that have been thrust upon them. There are no additional characters on hand except as these are mentioned in conversation. With only the simplest set design (by Tanya Orellana) to mark the place, and changes in body language to mark the passage of time, it is essential to listen carefully to both what is said and what is left unsaid as we follow the pair through their lives. Together, apart, and together again. The Zen of living.