Ottessa Moshfegh has a cult following.
The author, known for her books like "My Year of Rest and Relaxation," "Death in Her Hands" and "Lapvona," took this into account when co-writing the screenplay adaptation for her 2015 debut novel "Eileen."
Moshfegh tells TODAY.com she wanted the adaptation, which she co-wrote with her husband Luke Goebel and premiered in theaters nationally on Dec. 8, to stay true to the book to honor her readers' devotion to the original.
"I think they could trust me to know that I wouldn’t let them get away with something that no one would like, obviously," Moshfegh tells TODAY.com cheekily.
As Moshfegh starts to dish on the differences between her novel and the movie, the film's director, William Oldroyd, who's sitting beside her, leans over and whispers something in her ear.
"Will just whispered, 'It's much better,'" Moshfegh says through laughter. "If you read the book, then you either love it or you hate it. And I think if you watch the film, you might—"
"Only love it," Oldroyd interjects with a grin.
"You might love it," Moshfegh continues, laughing again. "But you also might want to go read the book, because both are mysterious. I mean, both have a certain element of shock and seduction and repulsion. They're complete experiences, and I think they both leave you hungry for more."
Oldroyd says one of the biggest differences between the book and the film comes down to when the character of Rebecca (Anne Hathaway) is introduced to the audience.
"One of the things we found in the adaptation is that Rebecca comes in halfway through the novel. But in the movie she comes in really early on," he says, adding she's in the film within the first 15 minutes or so.
Due to the speed at which Rebecca is introduced in the movie, Eileen's antics before she meets Rebecca in the book are left out of the film, including her relationship with her sister, her many fantasies about her co-workers and context on how her father became an alcoholic.
For this reason, Oldroyd offers a blistering hot take: "I would also say go to the movie first and then read the book."
"People have said to me, who knew neither, that they were glad they knew nothing about it going in," Oldroyd says. "But then I say to you, when you’ve seen the movie, then go read the book... because there’s half a book of Eileen’s life before Rebecca comes, which is really fantastic to read."
The ending of the movie is also left on more mysterious circumstances than the book. In the novel, after committing a shocking crime with Rebecca, Eileen abandons her car and hitchhikes her way to New York City. She asks people to call her Lena and changes her last name when she gets married a few months later.
At the end of the film, Eileen still hitchhikes and catches a ride with a truck driver, but the final scene shows the truck driving down the highway, with the fates of Eileen and Rebecca left unclear.
"I know I personally could watch 'Eileen Part Two.' Like I'm dying to know what happens," Moshfegh says. "I think the book is one thing, and the movie is another thing. If you like going to movies, you should go to the movies and see this this one, because it's really cinematic. It's really fun to watch in the dark in a theater full of people."
Moshfegh and Oldroyd both agree the film is a faithful adaptation of the book and that the feedback so far has been positive.
"I think the people who have loved the book and have seen the movie have found it to definitely be in the spirit of the book. Like, haven't received any death threats yet," Oldroyd jokes. "Not yet."