Reese Witherspoon Praises Taylor Swift's 'Haunting' Original Song for 'Where the Crawdads Sing' (Exclusive)

The 'Where the Crawdads Sing' producer was thrilled to have Swift contribute an original song to the soundtrack.

As soon as Reese Witherspoon read Delia Owen's 2018 bestseller, Where the Crawdads Sing, she knew she had to bring the story to the big screen.

"I read this novel probably in one day, maybe two days, I just couldn't put it down," the actress and producer says in ET's exclusive look at the set of the upcoming drama, which stars Normal People's Daisy Edgar-Jones as Kya, the central figure in the story. Where the Crawdads Sing was first featured in Witherspoon's namesake book club before being adapted into a feature film by an all-female creative team, including director Olivia Newman and screenwriter Lucy Alibar.

The book and film tell the tale of Kya's life as a girl who grew up alone in the swamplands of North Carolina before being thrust into the spotlight in a nearby town after a local football star turns up dead near her home.

"You really don't know if she did it," Witherspoon explains of the tumultuous story. "She's been so outcast in society, she's been treated so poorly by people that it's really possible that she might have committed this crime."

"This film is so many things," adds Edgar-Jones, who used her past experience as a competitive diver for some of the film's intense underwater scenes. "It's a love story, it's a a story about nature, a story about survival. But it's also a sort of courtroom drama, and there's this really big thriller aspect to the film."

Bolstering the film's haunting themes is an original new song from Taylor Swift, titled "Carolina," which she wrote specifically for the end credits -- and has sparked buzz about the singer earning her first Oscar nomination for Best Original Song.

"She was so inspired by the book," Witherspoon says of Swift's contribution. "It's haunting. It's beautiful and it's just the perfect way to end the whole movie."

Where the Crawdads Sing is in theaters July 15.