'Gone Girl' Gets A Different Third Act Than Novel

David Fincher's film adaptation of Gone Girl will get a different ending than its source material.

Gillian Flynn, who wrote the bestselling novel on which the film is based, told Entertainment Weekly that the third act will be entirely different than the one in the book.

"Ben [Affleck] was so shocked by it," she said. "He would say, 'This is a whole new third act! She literally threw that third act out and started from scratch.'"

Flynn, a former television critic for EW, admitted that she got a rush from changing the ending.

"There was something thrilling about taking this piece of work that I'd spent about two years painstakingly putting together with all its eight million LEGO pieces and take a hammer to it and bash it apart and reassemble it into a movie," she said.

In the same issue, David Fincher said the lesson he learned from the film adaptation of The Girl with the Dragon Tattoo was that "we may have been too beholden to the source material."

Back in September, Gillian Flynn confessed that Fincher was her "all-time favorite director," and that she dreamed of him making Gone Girl into a movie. She also said that she was surprised by the book's success because it wasn't something that "screams bestseller."

Gone Girl also stars Rosamund Pike as Amy Elliot Dunne, Nick Dunne's (Affleck) wife who goes missing on the day of their fifth wedding anniversary. Nick is left as the prime suspect, but Amy's disappearance isn't exactly what it seems. Fincher said he likes taking on unconventional characters.

"I don't know what 'likable' is," he said. "I know people who are doting parents, who give to charity, drive Priuses, all those things, who are insufferable a**holes. I like people who get s**t done."

Gone Girl hits theaters October 3.