If all that distinguishes stage acting from film and television acting is the size of the performance, Cynthia Nixon might be an ideal Jean Brodie for the Lifetime network. But in Jay Presson Allen's play The Prime of Miss Jean Brodie, adapted from Muriel Spark's novel, if the benignant and coy Scottish schoolteacher Nixon is now playing might perhaps merit an Emmy nomination, it has no place on a stage.

Even in a theater as small as the Acorn at Theatre Row, the emotional colors undoubtedly roiling within Nixon seldom read past the first row. Nixon's Brodie, the Italy-enamored progressive instructor at Edinburgh's Marcia Blaine School for Girls, is a cool and calculating monster who tries to effect her will on her students, her men, and even her audience with sly subterfuge rather than the fiery histrionics usually associated with this star-making role.

Nixon, of course, is already a star, as several seasons of Sex and the City on television and a hefty theatre resume will affirm. So it's perhaps understandable that she and director Scott Elliott would want to bring Brodie more down to Earth: This allows Nixon to put her own unique stamp on a role that's already been interpreted to galvanic, scenery-chewing perfection by actresses like Vanessa Redgrave (in London), Zoe Caldwell (on Broadway), and Maggie Smith (on film). But as Earth is alien territory for Brodie, this was not the wisest choice.

Seeing herself as the sole combatant against convention and conservatism, Brodie has devoted the best years of her life at the school to creating her own army of elite girls who will counteract the prevailing wisdom of the masses and give voice to the drowned-out innocents longing for the safety of Fascist rule. Oh yes, and provide her the power- and ego-boosting support her own ego requires.

This is not a small woman, or a woman with small ideas. She rejects authority, most fervently of the kind represented by the school's headmistress; she disdains marriage, taking up with a number of men and leaving her own indelible imprint on them (Mr. Lloyd, the art teacher played here by Ritchie Coster, becomes so obsessed that all his paintings' subjects soon resemble her). When she turns to the audience, ostensibly magnetizing her students, we know she's attempting to seduce us as well. And when she presents the world, and fashions her arguments, in ways that leave no rational room for argument, how could she not succeed?

As it turns out, quite easily. To make Brodie a huge figure simply wrapped in a diminutive package, an actress would need to convince the audience of the continuous presence of the vibrant, erotic inner life she only fully unleashes behind closed doors. But as Nixon never consistently connects with Brodie's unchecked sensuality, you quickly come to feel you're watching an amplified, Caledonian version of her Miranda from Sex and the City: a brr with a burr.

She dons her libidinous properties only occasionally, and then only as she might a warm winter jacket. You sense, from Nixon and Brodie alike, an actress playing a role for which she's not ideally suited, under circumstances that don't allow her to bring forth enough of her innate appropriateness to make a difference. When the students comprising her "crème de la crème" take her lessons into the world, and either pay the ultimate price or use them to repudiate their role model's influence, Brodie's tacit annoyance never gives way to shattered betrayal. As we never believe in Brodie, it's hard to accept that her students would.

Of the girls, Zoe Kazan stands out as the one who means the most to Brodie, and learns the most about destroying her. Betsy Hogg's doomed innocent, Halley Wegryn Gross's steamy sunbeam, and Sarah Steele's stuttering bystander all have their moments, but don't conjure spells of their own or convey having fallen under Nixon's. Coster and John Pankow, as the enamored music teacher, better communicate Brodie's emotional reach; Matthew Rauch and Caroline Lagerfelt carefully polish the potentially clumsy flashback frame that gives rise to the bulk of the story, and places the action in its proper historical context.

Neither Elliott nor his designers (Derek McLane for sets, Eric Becker for costumes, or Jason Lyons for lights) do enough themselves to establish the 1930s setting that crucially anchors the action between the World Wars, in a time when Brodie's ideas could conceivably represent a developing threat. As the only evidence of Elliott's working with Nixon to inject Brodie with detectable passion emerges from Brodie's second-act tirade about oppression in fierce defiance of Headmistress Mackay (Lisa Emery), this is not surprising.

What does raise an eyebrow or two is that an electric Brodie might well be sharing the stage with Nixon. As the patrician Mackay, Emery gives a gripping performance that makes the headmistress's quest to unseat Brodie the play's true driving concern. Without breaking a sweat and practically without raising her voice, Emery transforms a potentially unsympathetic foil into a charismatic crusader in her own right, one who could believably topple Brodie's regime with our implicit approval.

This is what any Jean Brodie needs, and hopefully Emery will someday have her crack at the role. While she's sadly unlikely to get that chance in New York unless she first stars in a major TV series herself, it's at least comforting to know that the Jean Brodie absent from the Acorn is alive and well and living in her. But if Nixon ever possessed the proper qualities to embody her, this great actress is seemingly past that particular prime.

The Prime of Miss Jean Brodie
Through December 9
Acorn Theatre, 410 West 42nd Street
Tickets online and current Performance Schedule: TicketCentral