Why Reese Witherspoon Isn't the 'Gone Girl' and 3 Other Secrets From the Fall Thriller

When a novel becomes a bestseller, Hollywood usually comes knocking. In the case of Gillian Flynn’s 2012 hit novel Gone Girl, Reese Witherspoon was the one at the door looking to nab the rights. Part psychological crime thriller, part twisted love story, Gone Girl is the saga of a man named Nick, who’s suspected of murdering his missing wife Amy. The movie, due in theaters Oct. 3, stars Ben Affleck, Rosamund Pike, and not Witherspoon, who ended up producing. Entertainment Weekly’s new issue, on stands Friday, reveals why Witherspoon isn’t in the hotly anticipated movie, along with more secrets about bringing the book to the big screen:

1. Reese Witherspoon bowed out gracefully.

Witherspoon is a producer on the film and obtained rights to the book in order to play the role of Amy (the part that now belongs to Pike). But director David Fincher had other ideas. “I think it would be awkward to have somebody who is starring in a movie and producing it,” he told EW. The Oscar-winning actress complied, saying, “He told me a vision for what the characters were, and it was very clear that I was not right for his vision.”

2. Ben Affleck didn’t need research.

The 41-year-old Oscar winner already knows what it’s like to live under a 24-hour media microscope, something he has in common with his character Nick. “I knew what it was like to have the tabloid world paying attention to me and ascribing negative motivations to whatever I might be engaging in,” he told EW. “I knew what it was to be cast in the soap opera I had no control over.”

3. Pike didn’t just beat out Witherspoon for the role.

The 35-year-old British actress reportedly won the role over Natalie Portman, Emily Blunt, and others. She also says she modeled her Gone Girl character after the late Carolyn Bessette-Kennedy, the beautiful and mysterious wife of John F. Kennedy Jr., who died with him in a 1999 plane crash. “You never heard her speak,” Pike told EW. “You just see those pictures of her hiding her face. The way she moved — I used quite a lot of that body language and mood. She’s the dream girl. That’s what Amy was for Nick.”

4. The ending has changed…or maybe not.

Fans of the book went batty when Fincher told EW back in January that Flynn, who wrote the screenplay, made what sounded like serious revisions. “Ben [Affleck] was so shocked by it,” Fincher said. “He would say, ‘This is a whole new third act! She literally threw that third act out and started from scratch.’” Afterwards Flynn pulled back from that, telling fans in a Reddit AMA that the reports were “greatly exaggerated!”

Now Fincher may be muddying the waters again. In a cryptic explanation (via Vulture), he told EW that what has changed about the final act is “everything and nothing.” He then referenced changing “the bone structure and the muscles and the skin. And the hair,” and ended this curious metaphor by saying, “But at its core, it’s exactly what I think Gillian always intended.” We’ll all find out for sure when Gone Girl hits theaters on Oct. 3.