The Murderous Rage of Quiet Mrs. Cage : A taut one-act play probes the mind of a middle-aged woman whose submissiveness was once expected by society but is now scorned

Nothing much actually happens in “Mrs. Cage.” A well-dressed, middle-aged woman sits in a chair and--mostly unemotionally--recounts the murder she committed that morning.

It wasn’t a crime of passion, at least in the conventional sense. Mrs. Cage was doing her daily grocery shopping when a thief snatched the purse of a fellow shopper--a young woman she didn’t know. A box boy intervened and was shot by the thief. When he dropped the gun and fled, Mrs. Cage picked it up and killed the young woman.

Those are the facts, ma’am. What unfolds in Nancy Barr’s taut two-character one-act (at Two Lights Studio in Santa Monica) is the story of Lillian Cage, and what brought her to a point of such incoherent rage that she could gun down a complete stranger. She will tell the policeman everything he wants to know. We learn about her 33-year marriage to successful attorney Martin Cage, her uneasy relationship with her divorcee attorney daughter, her quiet days of shopping and housekeeping.

“I identify with that generation of women,” said the playwright, 35, “that silent majority who didn’t think they were oppressed or of little value--who thought they made valuable contributions. A lot of the success of this woman’s marriage--or its duration--has to do with humility, a willingness to subjugate herself. And she finds herself in a society now that not only doesn’t appreciate her, but scorns her. The sad thing is that women have kind of ganged up on other women, confused liberation with arrogance and greed.”

Although Barr has always worked--as a waitress during early actressing days and more recently as a story analyst at Creative Artists--she finds the idea of staying home and tending to husband and child neither off-putting nor embarrassing. “That whole thing about Mrs. Bush and Wellesley, I felt like, ‘Hey, lighten up,’ ” she said, recalling the flap over the First Lady’s suitability as the college’s commencement speaker last summer. “She shouldn’t be disparaged for being just a housewife.”

It’s an issue that strikes a personal chord. Although Barr is serving double duty as the author and director of “Mrs. Cage,” her happiest and most consuming role is playing mother to her child, 21-month-old Barney. “It’s very enlightening--and not at all what I expected,” she said blissfully. “I’d gotten the impression there was a lot of drudgery involved. But it is the best relationship. You love a child more than you can imagine you could love anything.”

Born in Toronto, Barr moved to the San Gabriel Valley when she was 10. After theater studies at UC Davis (“It was the UC campus farthest away”), she moved to New York for a short stint at New York University’s graduate school, eventually drifting away from acting. “I was always more of a homebody,” she said. “It was hard to go out every day and bang on doors.” She shifted toward writing. Barr’s first play, “While I Waited for Wa,” bowed locally in 1983, followed by “Two by Barr” (the one-acts “Johnny Dakota Writes It Down” and “The Happiness of Fran”) in 1984.

Although she wrote “Mrs. Cage” in 1985, it was in an incomplete state; Barr admits that she “had to be encouraged” to finish it. Her own motivation came through helping Judith Weston, an old buddy from acting days at the Berkeley Stage Company.

“I’d had a real bad thing happen to me, a betrayal, and I had a hard time recovering from it,” Weston said. “It was like, ‘Should I get out of bed today?’ and it just kept getting worse. Then Nancy said, ‘I think the only thing that’ll help is doing some art.’ ”

Weston has found the role both “liberating and very, very difficult”; her performance--opposite Charles Bouvier as the interrogating police lieutenant--is a stunner. “It required a lot of detective work,” the actress said. “My life is not hers. I haven’t been married 33 years; I don’t have a child. But I loved this woman. I felt very connected to her from the start, a deep compassion and recognition--recognition of her loneliness and her attempts to deal with it, her gallantry, her honesty, her discipline within her own moral code.”

Barr (who also dubs Mrs. Cage “fastidious, proud, humble and tragic”) drew the character “from a lot of homemakers I’ve known,” and emphasizes that the specifics are completely fictional. “I thought I was going to write an unrequited love story between this woman and a box boy,” she said. “But it was one of those situations you hear about where the character kind of takes over. I knew her voice, her husband’s, her daughter’s. It was always going to be two characters, and she was always confessing. One night I got home from work, started at 7 at night and, at 7 in the morning, there it was.”

“Mrs. Cage” plays indefinitely at 8 p.m. Fridays through Sundays at Two Lights Studio, 1755 Lincoln Blvd., Santa Monica , (213) 466-1767. Tickets are $10.