SOURCE THEATER'S production of "The Aunts" marks the promising debut of Washington playwright Gary Bonasorte. As is to be expected of any first play, Bonasorte's comedy/drama has its share of bumps and soft spots.

Strong on characterization but somewhat weak on dramatic motion, it often feels more like a short story than a play. But director Bart Whiteman is sensitive to the play's virtues, and the good performances make a visit with "The Aunts" two hours pleasantly spent.

Bonasorte finds humor and hurt in the lives of three lower-middle-class Pittsburgh women who spend a weekend carping and consoling and hanging out together. The two older women, sisters, are struggling in unhappy marriages they were trained to accept unquestioningly; they hope to save their niece, the third woman, from rushing into the same fate.

Aunt Meg escapes her lousy home life by drinking and hiding out in sister Nan's house. Upstairs, Nan's husband Don is dying painfully from cancer, leaving Nan little time to consider her reaction to the impending separation. Niece Pita arrives breathlessly from cashier training school. Given to overeating, she leads a social life that consists largely of attending showers and weddings and fretting about whether she can turn her unwilling boyfriend into a fiance.

Besides affectionately drawing his fully- fleshed characters, Bonasorte shows a flair for comic stage business: A particularly appealing tableau of the three women swings between giddiness and self-pity as they gobble pot brownies (originally baked to ease Don's pain) and assemble wedding favors (mints in plastic swans with wedding bells, ribbon and gauze).

But Bonasorte seems to run out of inspiration in the third act, and the play's themes resist being stuffed into his neat, uplifting conclusion.

Whiteman has advised the actresses to underplay, and they are as natural as can be. As ashtray-voiced Aunt Meg, Ann Content is indomitable, a blend of bitterness and briny wisecracks. Pat Murphy Sheehy is drained and drawn as Aunt Nan, with a surprising solidity and sweetness beneath her careworn features. And Brilane Bowman, giving a note of comic desperation to sweet, dim Pita, is always funny and touching, whether talking while stuffing chicken curry in her mouth or abruptly switching her voice to a tooth- decaying coo when calling her boyfriend.

Whiteman also designed the perfectly homey and homely setting, and from the look of "The Aunts" and other recent offerings, it seems Source's modest production values are on the upswing.

THE AUNTS -- At Source Theater Main Stage through March 22.