"Brotherhood," the family drama that opened Sunday night at the New Playwrights' Theatre, is tantalizing . . . as far as it goes.

Time and again, playwright John Richardson seems to be on the verge of telling us what's obsessing him in this account of three midwestern brothers, their estrangement and their tentative reconciliation after the death of the eldest in Vietnam. But at the last minute, he invariably pulls back, leaving us grasping for the dramatic sense of things.

"Perhaps the key to how the play works is how much is missing," Richardson explains in a program note, adding that he wants an audience to confront the "vague sense of loss" experienced by his characters. Too much is missing, however. While stage characters often have a vague sense of their lives (see Chekhov), a playwright communicates sk,1 sw,-1 that nebulousness mainly by being as specific as possible (see Chekhov again).

Richardson's chief innovation is to superimpose the events of two summer evenings -- one in 1969, the other in 1981 -- making "Brotherhood" the theatrical equivalent of a double exposure. The eldest brother, Digger (Christopher Hurt), a beer-swilling marine, has died on the battlefield by 1981, so we see only his earlier incarnation. But the other brothers -- Chuck, a fretful student, later a successful lawyer; and Jack, a pot-smoking hippie who turns into a globe-trotting wastrel -- are each incarnated by two actors playing their younger and older selves.

The main thrust of the summer evening in 1969 seems to be Digger's attempt to instill some kind of self-worth in his younger brothers before he runs off to reenlist. In 1981, Chuck and Jack are coming home for the funeral of their father, a prominent judge, and clash over the settling of the will. What is Richardson trying to illuminate with this intermingling of then and now?

Festering sibling rivalries? The guilt induced by Digger's death? The heritage of the absent father? At one point in 1969, Digger forces his brothers to chant repeatedly, "I am my father's son." "So what?" finally replies an uncomprehending Chuck. "That part's up to you, smart boy," retorts Digger. The evasiveness of the reply is characteristic of "Brotherhood" as a whole.

Paradoxically, the play is persuasively staged by William Partlan and acted by a cast of five young actors, who have succinctly captured the familiar and antagonistic ways brothers relate to one another. Everything about this solid production, set in a realistic midwestern back yard complete with basketball hoop above the garage door, seems to promise the very revelations that are not forthcoming.

Hurt is splendid as Digger -- half bully, half mentor to his younger brothers -- and he's managed to convert the aggressive air he usually projects on a stage into something approximating love, without losing any of his cockiness. Christopher Pickart and Paul Morella are well-matched embodiments of Chuck, the "skinhead" turned button-down lawyer. And Rick Foucheux's anguished dissipation, as the latter-day Jack, is the perfect extension of Mark Mendez's careless flower-child airs.

I believed them all, just as I believed that they were grappling with real feelings of confusion and anger. In "Brotherhood," Richardson is struggling to come to terms with his own past, but I suspect he won't have a fully developed play until he resolves the conflicting emotions in his own heart. Right now, he's asking us to do that job for him.

Brotherhood. By John Richardson. Set, Michael Franklin-White; lighting, Daniel MacLean Wagner; costumes, Jane Schloss Phelan. With Rick Foucheux, Christopher Hurt, Mark Mendez, Paul Morella, Christopher Pickart. At the New Playwrights' Theatre through April 27.