Very faithful, David Fincher agreed to work with the book’s original author, Gillian Flynn, after reading her initial draft. Flynn remained with the film for the entire process, a rarity in Hollywood where book authors typically write no more than a first draft and an endless line of screenwriters take over for the duration of the project. (This is somewhat characteristic of Fincher, though, as he’s known for his close collaboration with his screenwriters. For example, Aaron Sorkin was the sole writer of The Social Network and present throughout the entire project, even “directing” the final shot of the production at Fincher’s request in a show of professional courtesy.)

[SPOILERS]

While the film remained faithful to the book, a substantial material had to be taken out. This is typical with novels (especially those as long as Gone Girl) since they’re typically too dense for a complete translation into a feature film of conventional length. Most of the material dealing with the characters’ parents were dropped, including flashbacks of Nick’s mother and Desi’s mother. Even the ending was streamlined, with some notable details dropped as well (Nick’s book, Amy’s anti-freeze tainted vomit). The one significant addition was the talk show interview, which shored up the film’s critique of the media and its relation to society.