Cooper spent six years working on this project -- and for five of them, sometimes several days a week; he worked just on the voice. He says he took a chance on this project, saying he realized he wasn't sure he could pull it off.
So it's a good thing producer Scott Stuber saw Cooper's vision of bringing Bernstein's story to life.
"As much as Scott Stuber trusted me, I trusted him. That's at Netflix, because everybody passed but him, all around town," said Cooper. "And in the end, you know, when I was, like, 'Okay, this is it.' And they were, like, let's go."
Mulligan also spent considerable time being involved with this film, playing '50s actress Felicia Montealegre, someone who knew exactly who she was marrying.
"She wrote him a letter before they got married. She says, 'You are a homosexual and you may never change' and something along the lines of, 'I think we can make a life together without me sacrificing myself with as a martyr to altar of L.B.,'" said Mulligan. "So there was no part of her that was seeing herself as a victim of this when she entered into it. And I think, you know, she was a huge part of his creative endeavor, I think."
Also a huge part of the movie: cigarettes. I told Cooper I worried about his health.
"Yeah, so was my mother. The character, I'm sure glad you brought that up, because cigarettes are a character, and especially for Felicia and everything that has to do with smoking and the lighter because that is -- we're watching Felicia kill herself throughout the whole film," said Cooper.
"Maestro" is a beautifully put together film with strong performances, a great look and a fascinating story. The film is rated R.