Lydia Tár is a rarity. She’s one of very few women who have become conductors of major orchestras — but it turns out, she shares some of the same predatory qualities as men who preceded her.

In the first scene of “Tár,” she’s being interviewed at the New Yorker Festival by that magazine’s Adam Gopnik, and it’s clear she has reams of knowledge of classical music. Unfortunately, as a viewer, I felt like a college freshman who accidentally signed up for a graduate music theory course without having taken any of the prerequisites, so it was all over my head. Sadly, that feeling never abated while watching the movie.

As Tár, Cate Blanchett uses every molecule of her massive talent. She never looks like an actor pretending to be a conductor — she learned how to do the job, and pulls it off brilliantly. The same goes for her playing piano and speaking German (although it’s odd that some of her conversations are subtitled in English, while others aren’t, and she changes back and forth on a whim).

As the plot develops, we see how manipulative Tár can be and how easily she lies to those around her professionally and personally, including her wife. But it’s not until the second half — when she sets her eyes on an attractive, talented new cellist — that we see her exploitative side come out, and learn it’s far from the first time she’s crossed that line.

Despite its star’s best efforts, the movie is way too long at over two and a half hours, and it feels so much longer because of the slog that is its first hour. I would have enjoyed “Tár” much more if director Todd Field had given us more scenes of her working with the orchestra and fewer of her fighting her inner demons while jogging through the streets of Berlin.

I give “Tár” a 3 out of 10, purely for Blanchett — who may end up with an Oscar nomination — but I don’t know who the expected audience is.

Opens Friday in theaters.