To theater buffs, the thought of 2006 Tony winner Cynthia Nixon playing the dangerous Miss Jean Brodie — a role made famous by the likes of Maggie Smith, Vanessa Redgrave, and Zoe Caldwell — was pure catnip. So it is with some disappointment that I report the New Group’s revival of “The Prime of Miss Jean Brodie,” which opened Monday, is merely a very competent one.

The normally fleet-footed Ms. Nixon, struggling under the weight of an uncomfortable Scottish brogue, never fully disappears inside the incomparable Miss Brodie. And though she’s undeniably magnetic, Ms. Nixon seems too contemporary a figure to belong to a 1930s Edinburgh girls’ school.But if Scott Elliott’s efficient production doesn’t dazzle, neither does it bore; we hang on the every word of its two lionhearted heroines.

The first, the cooly elegant Miss Brodie, is a revered and controversial teacher at a decidedly conservative school. She has a complexion like cream and a soul like curdled milk; this is someone to be both loved and feared. The play’s second heroine, a schoolgirl named Sandy (Zoe Kazan), is as plain as Miss Brodie is fair, but behind her flinty eyes lurks a hardhearted intelligence far beyond her years.

Like many pupils, Sandy experiences the classroom version of Miss Brodie — reminiscing about her tragic pre-war love affair, preaching proper skin care, rhapsodizing about Giotto and Mussolini. But Sandy is also one of a select few chosen to be part of the “Brodie set,” a club of four that accompanies Miss Brodie to museums, theaters, and weekly al fresco picnics with the music teacher, the very eligible Mr. Lowther (John Pankow).

Sandy, according to Miss Brodie, is the “dependable” member of the set, but Jenny (Halley Wegryn Gross) is the pretty one, and Miss Brodie, giving us our first glimpse into her alarming interior, declares her high hopes that Jenny “will be famous for sex.” Jenny, Miss Brodie decrees, shall be a D.H. Lawrence heroine to whom (most cherished of all Brodiean fantasies) “the common moral code will not apply.” To speed Jenny’s development, Miss Brodie — boldly defying the common moral code — sends the young girl to the portrait studio of a dissolute art teacher, Teddy Lloyd (Ritchie Coster) — himself a spurned lover of Miss Brodie’s.

What Jay Presson Allen’s adaptation (of the 1962 Muriel Spark novel) captures so vividly is the fateful match between Miss Brodie’s delusions and the yearnings of youth. Miss Brodie’s obsession with the “crème de la crème,” with who will or will not wind up among “life’s elite,” plays right into the girls’ natural tendencies to rank and punish; before long, Sandy is enforcing her own petty little hierarchy on the Brodie set. Miss Brodie’s stories about romance, tinged with just the slightest whiff of sex, correspond to the stage of the girls’ own budding fantasies. The girls can’t stop themselves from making Miss Brodie the heroine of the slightly dirty story they write in a composition book.

Tellingly, the real danger for the oft-reprimanded Miss Brodie only begins when her girls outgrow her. In the scene in which a brazen Sandy sits nude in Teddy Lloyd’s studio, a cigarette between her world-weary lips, it’s obvious that the experience of cold, transactional sex with a married family man (and a teacher) has hurt her. But Sandy is the kind of girl whose pain makes her sharper, harder; soon, she’ll be adamantine enough to rival Miss Brodie. Ultimately this is to be Sandy’s play — she will grow up to be the cloistered nun remembering these events in flashback (the play’s rather creaky framing device).

Ms. Kazan gives a fresh, disarming performance as Sandy, growing from hawk-eyed girl to chillingly bold teenager before our eyes, with each turning point registering on her wonderfully expressive face. At every moment, we’re aware of her yearning for love and her fear of rejection, and of the preternatural confidence that drives her too early into the darker recesses of the adult world. Under Mr. Elliott’s adept direction, the four Brodie girls and the two male teachers form a convincing circle of admirers, and Mr. Elliott’s mostly crisp staging has the effect almost of a camera lens, keeping the focus squarely on the performers.

It’s Miss Jean Brodie herself — in all her mercurial, delusional glory — who never fully persuades. The main trouble is that Ms. Nixon doesn’t do the accent — the accent, unfortunately, does her. And though she doesn’t let it distract her, it distracts us.

There’s also, however, a fence-sitting quality to the performance. On the page, Ms. Brodie charms one moment and draws blood the next; here, she’s chilly in both modes.There is so little of the outré in Miss Brodie’s outward demeanor that it can be hard to reconcile her persona with her more outrageous statements.

For all that, Ms. Nixon has charisma to spare; you can’t take your eyes off her, and when she comes to the very edge of the stage to teach, eyes flashing, she momentarily makes pupils of the whole audience.And in Miss Brodie’s late, climactic showdown with the school principal Miss Mackay (the excellent Lisa Emery), Ms. Nixon spews fire. Here at last is Miss Jean Brodie — a woman of endless contradictions who sees none of them, a habitual transgressor who believes in her own innocence to the bottom of her soul, a woman in whom conscience has been replaced by a tenacious vanity.

Until December 9 (410 W. 42nd St., between Ninth and Tenth avenues, 212-279-4200).