If you drew the story arc of "Tár," it would be a long horizontal line that ends with an angled, nearly vertical one. In other words, nothing happens for quite a while and then a whole lot happens at once.

For its first two hours, writer/director Todd Field's movie wants us to meet conductor Lydia Tár, a genius when she's leading her orchestra in Berlin but a horrendous person offstage. Manipulative, deceitful, demanding and rude, she shows us who she is when she threatens a pre-teen bully on a playground and, perhaps more to the point, when her assistant mentions International Women's Day and she has no idea what that is. There's not a lot of plot in "Tár" but you can consider that last detail foreshadowing, since it turns out Tár is accused of mistreating a series of young female musicians.

If you're up for a character portrait, "Tár" is a fine one. Its title character is a fascinating study in whether it's possible to separate artistic output from behavior (in an onstage interview with New Yorker writer Adam Gopnik, Tár says it's possible). Does Tár realize how awful she is? Is she so devoted to music that she doesn't think about anything else — including her wife (the brilliant Nina Hoss) and, possibly, daughter? Has she convinced herself she must satisfy her selfish desires in order to create the aural beauty that is her calling? What does it mean that her life is classical music but she only listens to jazz at home?

These kinds of questions consume the rigorous "Tár" — as opposed to the question that consumes most big movies these days: "Will that special effect succeed in destroying that other special effect?"

As Tár, Cate Blanchett is endlessly fascinating. In that Gopnik scene, she seems ill at ease — the actor, not the character. Studied and stiff, Blanchett doesn't convince us her character is responding spontaneously to the questions. That seemed like a problem to me until the end of the movie, when it occurred to me the lack of spontaneity may be a deliberate indication that Tár calculates every move, even those that seem impulsive.

I'm willing to buy that because the rest of Blanchett's performance is as wild and powerful as a mustang. She's entirely believable as a spirited conductor, as a woman who came up in a field dominated by men and perhaps decided to act like them, and as someone who doesn't give a damn if anyone understands her jokes about, for instance, René Redzepi (including most moviegoers, unless they've dined in Copenhagen).

Blanchett's single-minded ferocity prepares the way for an ending that will take audiences by surprise. Most of Fields' movie is as subdued as its protagonist is flamboyant — his camera barely moves and the sound is oddly muffled. It's a smart contrast because, along with Blanchett's blistering performance, those wild shifts prepare us to believe almost anything could happen.

"Tar"

***1/2 out of 4 stars

Rated: R for language, nudity and brief violence.

Where: In theaters