‘Horizon’ director Kevin Costner shocked Sienna Miller with phone call: ‘Be still my ‘90s heart’

“Horizon” star Sienna Miller’s shocking phone call with Kevin Costner began her latest career journey.

Miller, previously known for “American Sniper,” revealed how she became a part of Costner’s passion project, “Horizon: An American Saga,” in an interview with Fox News Digital.

“Well, I got a call. Be still my ’90s heart,” Miller, 42, revealed. “It said Kevin Costner would like to speak to you about a project that he’s doing. I then got four scripts, so I was like, it must be TV. It wasn’t. It’s for movies. And then there’s Kevin Costner on the Zoom, and I was beside myself. Anyway, we had a wonderful conversation. We got along very well. And at the end of it, he said, ‘Sienna, I have one question for you.’ And I said, ‘Yes, Kevin.’ And he went, ‘Will you go West with me?’ I died, I died.”

“I was like, ‘Yes, yes, I will go. I will go to the moon and back a million times,’” she recalled.

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Miller admitted she’d been a fan of Costner’s since “Dances with Wolves” and even named two of her pet rabbits after characters in the movie.

“I had Cleopatra, Thumper, Badger, Two Socks and Cisco,” she told Fox News Digital, naming one after the wolf and another after the horse from the film.

“I was a huge fan of that movie,” Miller added. “It broke my heart and [I] was very obsessed with Kevin from that moment forth.”

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Miller’s co-star Sam Worthington, known for his role in “Avatar,” explained what attracted him to Costner’s project.

“I just like working with directors that take risks and are trying to challenge themselves in storytelling,” Worthington, 47, told Fox News Digital. “That’s what we do on ‘Avatar.’ And with this, it’s a more traditional way of filmmaking. But at the same time, he’s not telling a plot-driven story.”

“He’s taken an almost like a novelistic approach to the journey of these characters – to this central character, which is the town of Horizon. And I thought that was a very unique way of approaching.”

Sam Worthington, photographed with wife Lara Worthington, was drawn to “Horizon” because Kevin Costner was trying to “challenge” himself with storytelling. (Getty Images)

“I just like working with directors that take risks and are trying to challenge themselves in storytelling.”

— Sam Worthington

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While all four parts of “Horizon” will showcase the West before and after the American Civil War, Costner’s storytelling reveals a bigger picture regarding the modern state of the country.

“I think that Kevin is telling a story that shows that there was a lot of hope in how America was formed,” Worthington explained to Fox News Digital. “And therefore, if [there’s] this hope in the formation of America, then maybe there’s hope in the continuation of America – whether it’s a Western or science fiction.”

“Good movies explain to us how we are now,” he added. “And so, if that’s his message, I think that’s a great message for the America that we’re in.”

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“I think that Kevin is telling a story that shows that there was a lot of hope in how America was formed.”

— Sam Worthington

Costner cemented his title as a great boss with the production of his Western.

Miller was pregnant while filming the second installment of “Horizon,” which is set to hit theaters on Aug. 16. The first film, “Horizon: American Saga,” will hit theaters seven weeks earlier on June 28.

“Kevin’s so sweet,” she admitted. “I told him I hadn’t told many people, so he was constantly bringing me little snacks and drinks. I just needed to eat all the time. If I was eating, I was fine. But you know, a few nauseous moments behind tents.”

Sienna Miller shared how Kevin Costner supported her while the actress was pregnant filming “Horizon: An American Saga – Chapter 2.” (Getty Images)

For Worthington, filming was an opportunity to learn from everybody on set with a cast brought together by Costner.

“I think everybody’s there for the right reasons to try and help him tell his story correctly,” he told Fox News Digital. “So, you’re learning kind of how they help each other to do the best for the boss.”

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Miller stars as Frances Kittredge and Worthington as Trent Gephart in the four-part Western saga. The two are joined by Luke Wilson, Abbey Lee, Jena Malone and Giovanni Ribisi.

“Horizon” also stars Costner, who wrote and directed the four films.

The 69-year-old actor backed the saga with his own money after deeming it a passion project nearly 30 years ago.

Kevin Costner spent decades creating “Horizon: An American Saga.” (Warner Bros.)

Kevin Costner not only starred in but also directed his film “Horizon.” (Warner Bros.)

“I know they say I’ve got $20 million of my own money in this movie,” he previously told GQ magazine. “It’s not true. I’ve got now about $38 million in the film. That’s the truth. That’s the real number.”

As the first “Horizon” film is set to hit theaters, Costner has officially turned his attention solely onto the saga – leaving his “Yellowstone” character John Dutton behind.

Costner explained he left “because there’s just too many questions about it.”

“So the time to step away was now,” he told Fox News Digital.

Through his deal with FOX Nation, Costner is set to release a new project in 2025 for the platform and previously hosted “Yellowstone: One Fifty,” a series that explores the origins of the national park.

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