With an ending that had audiences as gripped in as the rest of the story, it seems like David Fincher may have altered how he wanted to tie-up his latest film. Movie spoilers ahead.

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With the release of Gone Girl on Friday, Fincher adapted the best-selling novel by Gillian Flynn, who also penned the script. But it seems like both Fincher and Flynn decided to alter a little part of the ending to fit the movie better.

Cinema Blend broke down the film and book comparisons on Monday and at the end of the movie, Amy (Rosamund Pike) returns to Nick (Ben Affleck) after she sees, in television interviews, the apologetic version of the husband with whom she wants to spend her life.

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Nick, meanwhile, lures Amy back, but suddenly realizes he has invited this psychopath back into his life. "I know I'll never sleep again," he says in a line from the book, "I can't close my eyes when I'm next to her. It's like I'm sleeping with a spider."

Most of the scenes in the conclusion of the film come from the book. Nick meets with Detective Rhonda Boney (Kim Dickens), the only cop who still believes him, and they try to figure out a way to trap Amy in her lies. That plan is futile.

Amy gets pregnant in the book, and uses it as the ultimate blackmail to keep Nick at home. And it works. He succumbs to her final plan, and agrees to raise this unborn child, so he can protect the baby from its mother (how horrifying), and also, so he can strive to be a better father than Nick's own dad was.

But there are some changes. In Fincher's film, Nick and Amy hold a televised interview with Nancy Grace clone Ellen Abbott (Missi Pyle), announcing their pregnancy live to the nation but also giving Nick a chance to confront the media that had hounded him for weeks.

And there's a part in Gillian Flynn's novel where Nick takes the time to pen a manuscript - titled Psycho B---h -- that reveals all of Amy's secrets. Yet, in the book, he deletes it when Amy confronts him with the news of her pregnancy.

A few other details that were altered from the book was a trip to Hannibal, Missouri that Nick takes, no fear of blood by Amy, drunken confession by Nick, or the showing the murder of Desi Collings (Neil Patrick Harris).