The story of Helen Keller — the blind, deaf and mute woman who, with the help of her teacher Anne Sullivan, learned to communicate, becoming that rare woman to earn a college degree — has over time lost its rough edge. Trotted out now as a rote example of overcoming adversity, Keller has become divorced in the collective memory from her steely tenacity.

The Miracle Worker, William Gibson’s 1959 play based on Keller’s autobiography, did much to publicize her life, dramatizing her early encounter with Sullivan, herself a product of a school for the blind and a state orphanage. Coddled and pitied by her well-heeled Southern family, Helen lives like a wild animal, grazing off her parents’ plates at dinnertime and throwing vicious tantrums. Desperate to forestall institutionalization, the family summons Sullivan.

Teacher and student become locked in a battle of wills for Helen’s mind, the Yankee schoolmistress’ headstrong determination pitted against the girl’s frantic instinct for self-preservation. Their often physical tug-of-war, laced with slaps, scars and spit, can make for breathtaking theater. Led by some strong principal performances, Simi Valley ARTS’ new production directed by David Ralphe strives for but falls somewhat short of the grittiness needed to temper what can become a saccharine tale.

As the eponymous teacher, Sommer Branham brings pluck and determination to her portrayal of Sullivan. Channeling Maria Von Trapp and Mary Poppins in the early scenes, Branham’s lightly brogued Sullivan is initially too chirpy; she could use more of Anne Bancroft’s husky contralto. But Branham has many fine moments once she arrives at the Keller household. A feisty, spirited presence, she draws the focus, as she ought, in nearly all her scenes, also taking the brunt of the physical acting in her encounters with Helen.

This play lives or dies by its youngest star. As Helen, Natalie Esposito proves herself a talented young lady, evoking realism without devolving into a glassy-eyed cartoon. Her scowls and smiles reveal an intelligence we can intuit but not understand. The lovely actress, however, might have been better served by a more disheveled appearance. Pre-Sullivan Helen comes off as curious, bratty — but hardly the uncontainable hellcat driving the Kellers to their wits’ end.

The two actresses have impressive chemistry, but the staging often misses the bare-knuckle brawl dimension of their struggle. (Even so, Esposito and, presumably, Branham wear kneepads throughout.) The play’s best scene, a family breakfast that erupts into a battle royale when Helen snatches food from Sullivan’s plate, approaches the energy needed to sustain momentum throughout the rest of the play. But even here, in a series of traded almost-slaps, the production backs down. The hesitation is easily understood — who among us could hit a child? — but the restraint subdues the scene’s vigor.

Sean Harrington’s production design, despite a nifty pump that gushes real water, poses part of the staging problem. Significant real estate is devoted to Sullivan’s garret bedroom, where hardly any action takes place. Meanwhile, the family dining room, the locus of several important scenes, is squished stage left with little room to maneuver. When it comes time for Helen to hurl a spoon or overturn a chair, we’re peering through a thicket of heavy wooden legs and petticoats.

Ralphe has added some unexpected lyrical touches, like violinist Ray Dean Mize’s accompaniment with selections from blind composers. The strength of the cast, including strong supporting turns by Genevieve Levin as Mrs. Keller and Stephen Weston as her stepson Jimmy, takes us far. But perfection remains tantalizingly out of reach, a locked safe we can’t quite open.             

The Miracle Worker, through July 7, Simi Valley Cultural Arts Center, 3050 Los Angeles Ave., Simi Valley. 583-7900 or