Spoiler alert: We're breaking down plot points in Bradley Cooper's new movie"Maestro" (streaming now on Netflix). Beware if you haven't seen it yet.

Tackling a Leonard Bernstein movie means exploring a legend's major moments, significant relationships and, of course, diving into the composer/conductor’s masterworks. And in making the new Netflix biopic "Maestro," co-writers Bradley Cooper and Josh Singer had a “five-year listening party.”

“Some of Lenny's music is tough and challenging,” says Singer, who's written a few cinematic true-life tales including journalism dramas “Spotlight” and “The Post,” as well as space-race throwback “First Man." “But it's a lot easier to (study) that than figure out how to fly a Gemini capsule."

While certain aspects of "Maestro," directed by and starring Cooper, are painstakingly authentic, others are a result of some editorial creativity – like when Cooper’s Bernstein pulls up to Boston's Tanglewood Music Center in the late 1980s listening to R.E.M.’s lyric referencing him in “It’s the End of the World as We Know It (And I Feel Fine).”

“It wouldn’t surprise me,” Singer quips. His rule: “You can fudge a little” with time and place as long as “it doesn't change the meaning. But when you start to get into, 'Well, it really didn't happen this way,' that's where I start to get a little edgy.”

Singer walks through what’s real and what’s “fudged” in key scenes from “Maestro”:

Did Leonard Bernstein really become famous when a guest conductor called in sick for a Carnegie Hall performance?

An early scene finds Bernstein in 1943, when the then-25-year-old assistant conductor of the New York Philharmonic gets a 9 a.m. wake-up call after a night of partying. Guest conductor Bruno Walter has fallen ill and Bernstein is needed that night for a national radio broadcast, with no rehearsal. That not only happened in real life but it rocketed him to instant stardom. “The whole country was listening to Lenny conduct and it made him a sensation,” Singer says.

And Bernstein running downstairs and right into Carnegie Hall in his bathrobe? Singer says he would have been able to do that because he lived in an apartment above the famous venue.

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Did Leonard Bernstein have relationships with men before he met wife Felicia Montealegre?

“Maestro” explores Bernstein’s same-sex relationships, and one of the earliest is the composer’s closeness with clarinet player David Oppenheim (Matt Bomer). Lenny falls for and marries actress Felicia (Carey Mulligan), David starts a family with actress Ellen Adler, and the couples run into each other in the park, where Lenny and David share a touching moment. Lenny jokes to David and Ellen’s daughter, “Can I tell you a secret? I’ve slept with both your parents.” It’s a line Bernstein used frequently, as Adler’s daughter told Singer – Adler had also dated Bernstein for a time.

But Bernstein’s love for Oppenheim ran deep: He was best man at Bernstein’s wedding and many of Bernstein’s “most haunting pieces” feature clarinet, Singer says. He and Cooper peeked at letters between the two at the Library of Congress that “were just heartbreaking: You understand how these men loved each other. Lenny obviously had any number of lovers over the years, but those in particular struck us.”

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Did Jamie Bernstein actually confront dad Leonard about his sexual proclivities?

As “Maestro” moves into the 1970s, tensions arise between Felicia and Lenny when the composer finds a new companion in Tommy Cothran (Gideon Glick). Felicia wants her husband to talk to their daughter Jamie (Maya Hawke) about rumors of homosexual dalliances at Tanglewood – “Don’t you dare tell her the truth,” Felicia says – and Lenny lies to Jamie, chalking it up to professional jealousy.

Jamie wrote about that memory in her 2019 book “Famous Father Girl: A Memoir of Growing Up Bernstein,” which Singer and Cooper used in crafting parts of “Maestro.” “She's like, ‘I bet my mom put him up to it. Because my father, that was not what he did. He was someone who was more radically honest than not,’ ” Singer says. “When her book came out, it was super-helpful in terms of really being able to lean into some little specific moments like that.”

Did Leonard and Felicia really have a big fight during the Macy's Thanksgiving Day parade?

Felicia gets fed up with Lenny to the point of leaving his pillow, slippers and toothbrush outside their Manhattan apartment when he doesn’t come home at night. On Thanksgiving morning, Lenny shows up for the holiday festivities and he and Felicia get into a particularly nasty row. “If you’re not careful, you’re going to die a lonely old queen,” Felicia warns him, a gut punch of a line followed by the appearance of the Snoopy float in the Macy’s parade slowly passing by their window.

“That's a Bradley thing. He fixated on the Snoopy of it all,” Singer says. “We always knew we were going to get to a fight deep in the second act, and the fight is sort of mentioned in (Jamie Bernstein’s) book. Snoopy was mentioned as well, or maybe she told that to Bradley, and he wouldn't let it go.”

Did the couple reunite at Leonard Bernstein's famous performance of Maher's 'Resurrection' Symphony?

One of the signature scenes of “Maestro” is a six-minute re-creation of Bernstein conducting Mahler’s second symphony at England’s Ely Cathedral in 1973. He and Felicia are separated at the time, but after the big finish and as the crowd goes wild, Lenny heads backstage, passionately kisses his wife during the standing ovation and they get back together. 

“The music is literally the 'Resurrection' Symphony, and it is the resurrection of their relationship. So that felt right,” Singer says. But those things didn’t exactly happen in that order. While the concert was in ’73, the couple didn’t separate until the fall of 1976. And it didn’t last long. “By January, Lenny was like, ‘I can't do this. I miss her. This is not for me.’ And Felicia was also at that place of ‘I miss him, too.' ”

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