WILLIAM BRANGHAM: One of the year's most honored films is "Killers of the Flower Moon," which tells some of the harrowing story of how Osage Indians were murdered in Oklahoma in the 1920s.

And one of the year's most acclaimed performances is by one of the film's stars, Lily Gladstone, who's already making some of her own history.

Jeffrey Brown reports for our arts and culture series, Canvas.

LILY GLADSTONE, Actress: I love everyone in this room right now.

Thank you.

JEFFREY BROWN: For Lily Gladstone, it's been a season of fanfare, celebration and now an Academy Award nomination for best actress.

LILY GLADSTONE: Thank you all so much.

(CHEERING AND APPLAUSE) JEFFREY BROWN: You must be kind of high on life right now?

LILY GLADSTONE: That's one way to phrase it, yes, for sure.

(LAUGHTER) JEFFREY BROWN: Yes?

LILY GLADSTONE: Yes, it's been -- it's just been so touching to share this moment with so many people, just the response across Indian country, people I have never met, people I do know.

It's just -- it's really heartwarming.

JEFFREY BROWN: The film, in which she stars alongside Leonardo DiCaprio and Robert De Niro, is anything but heartwarming.

LILY GLADSTONE: Was he murdered?

LEONARDO DICAPRIO, Actor: Don't know.

LILY GLADSTONE: He tried to kill himself last year.

JEFFREY BROWN: "Killers of the Flower Moon," directed by Martin Scorsese and based on the bestselling 2017 book by David Grann, dramatizes the real-life history of the murders of dozens of Osage Indians, the precise number likely never to be known.

At stake, the oil discovered on Osage land and the riches that flowed from it.

LILY GLADSTONE: Are you scared of him?

LEONARDO DICAPRIO: My brother?

Who?

LILY GLADSTONE: Your uncle.

LEONARDO DICAPRIO: Well, no.

No, he's a -- he's a king of the Osage Hills.

JEFFREY BROWN: Gladstone plays Mollie, an Osage woman whose life and family become caught in the violence and loss.

Did it feel like an important story to you?

LILY GLADSTONE: Oh, incredibly, incredibly.

It's -- every native nation in the United States has had some kind of history where, especially if you're resource-rich, if you have something that's of value, then what that relationship is with energy development.

JEFFREY BROWN: Yes, first, that's land itself, right?

LILY GLADSTONE: Right.

Right.

Yes, land itself.

JEFFREY BROWN: It's a deeply important story personally as well.

Gladstone grew up on the Blackfeet Reservation in Montana just outside Glacier National Park, itself built partly on former Blackfeet land.

Daughter of a Blackfeet nation father and white mother who'd come to the reservation to teach, she refers to her childhood self as a nerdy rez kid who couldn't wait for the annual visit of the Missoula Children's Theatre, which gave kids an opportunity to put on a play.

LILY GLADSTONE: Nerdy, dorky, whatever you want to call it.

Yes, it was a little -- it was hard to place until I had theater as an outlet.

Then, suddenly, I had purpose.

Suddenly, like, kids were like, hey, Lily can do something.

That's cool.

JEFFREY BROWN: She would continue to act in high school when her family moved to Seattle and then in college at the University of Montana.

LILY GLADSTONE: So the Marines recruited you to speak Navajo.

I was asked early on by my adviser in college if I was going to try to only target Native roles and warned me that I would be pigeonholed if I did so.

And I have always resisted that, because I'm like, well, Native people are capable of everything.

We have doctors, we have lawyers.

We pop up every aspect of humanity.

So whatever character I play is naturally going to be imbued with being a Native woman, at least a little bit.

So, it's -- even if I am kind of smashed into a box, there's always a way of expanding it and breaking those boundaries, breaking the frame.

I just knew, if I didn't start driving, I wasn't going to see you again.

JEFFREY BROWN: She garnered notice in independent films, including 2016's "Certain Women," with an extraordinary ability to convey so much depth in the slightest change of expression.

"Killers of the Flower Moon" is her first major studio film, collaborating with the likes of Scorsese, DiCaprio and De Niro.

LILY GLADSTONE: There's going to be an element of impostor syndrome when suddenly you're thrust in the middle of the circle with these incredibly renowned actors.

And... JEFFREY BROWN: You felt that?

LILY GLADSTONE: A bit.

A bit.

But I had to hide it.

(LAUGHTER) LILY GLADSTONE: Because, really, when you get there, and you see the level of commitment and also the level of, like, questioning, it was refreshing to know that artists are constantly a little bit challenged and haunted by their work.

And it just felt at a certain point that I'd be doing these human beings that happen to be uber-famous, uber-renowned in their field, they're also searching, striving artists that need questions answered, and I was doing them a disservice if I was a little bit too leaned back or too nervous.

I had to bring something to the table too.

JEFFREY BROWN: Another vital collaboration, she says, was with the Osage people themselves, some of whom advised the director and actors along the way.

Gladstone says she and the others were concerned to get it right and honor the Osage people and their history.

(through translator): He's not that smart, but he's handsome.

ACTRESS (through translator): He looks like a snake.

LILY GLADSTONE (through translator): No, he's looks like a coyote.

I know that each one of these stories, while there's a universality that can be found in it, there's definitely common ground that you can draw from as a Native person from any nation in the states, it's also very specifically an Osage story and needed to be handled with just the utmost care and involvement.

JEFFREY BROWN: It is inevitably difficult terrain though, right?

Because even with all the critical praise and acceptance, there's some skepticism, criticism, even of, again, a story of Native trauma, in which the white people are centered.

LILY GLADSTONE: It's incredibly important that we're in a time where we have these incredible films and incredible television series that are led and crafted by indigenous people.

And it's also highly important that we have somebody as influential and as historic as Martin Scorsese caring about this history.

And, ultimately, what matters most to me and really, if I could sum up the one opinion of the film that mattered to me, the one person that I wanted to make happy, it was Margie Burkhart, Mollie's granddaughter, and then Osage community as a whole.

And I have been really touched to find just how protective the community has become of this film.

JEFFREY BROWN: Lily Gladstone recently became the first indigenous person to win the best actress award at the Golden Globes.

She greeted the crowd in the Blackfeet language, saying: "Hello, my friends.

My name is Eagle Woman.

I'm from the Blackfeet Nation."

LILY GLADSTONE: I'm really thankful that we're just in a time generally where people are seeing -- like, shifting the lens and shifting the focus into characters that have been on the fringe historically.

That's where -- that's where the interest lies.

It's where the stories that really resonate within a bigger audience are.

LEONARDO DICAPRIO: You know, you got nice color of skin.

What color would you say that is?

LILY GLADSTONE: My color.

JEFFREY BROWN: Next month, another huge stage, the Academy Awards.

For the "PBS NewsHour," I'm Jeffrey Brown in New York.