We didn't think it was possible for "Gone Girl," the thrilling, twisty, bestselling mystery by Gillian Flynn, to pack yet another surprise. But we were wrong, because according an interview with Flynn in Entertainment Weekly, even those who've read the novel won't know what's coming when the film hits theaters this fall. The author teased that the book's controversial ending is now something completely different -- describing the third act as rewritten "from scratch".

If you haven't read "Gone Girl," then read no further, because we're about to talk all about that ending, and how it might have changed.

SPOILERS AHEAD.

In the novel, the final third opens with Nick Dunne (Ben Affleck) awaiting trial for the murder of his wife, Amy (Rosamund Pike); though we know that she's still alive and that her disappearance is part of an elaborate plan to frame him. Amy, having hit a snag in her well-laid plans, has no choice but to return to her husband. And when the book ends, they're still married: Amy has blackmailed Nick into staying with her, supporting her, and continuing their codependent game of cat-and-mouse for all eternity. The reason? She's used his frozen sperm to impregnate herself with his baby.

In other words, the bad girl gets away with it and lives happily ever after. That is, if psychopaths were capable of feeling real happiness, which of course they are not.

It's hard to imagine how a resolution so crazy, so carefully constructed and so perfectly in keeping with the characters could possible be different. But if it's gotta change, then maybe it'll be something like:

Gone Girl Goes To Prison

A vocal contingent of readers who hated the ending have long wished for a more traditional whodunit resolution: one in which Amy gets caught and sent to prison, finally outsmarted by the man she'd manipulated. But it's hard to envision a version of "Gone Girl" in which Amy isn't always one step ahead of Nick, and Flynn herself has expressed that despite what critics might think they want, seeing Amy brought to justice would be totally unsatisfying. Might she have changed her mind?

Bad Outcomes All Around

What if Amy never reappeared on Nick's doorstep? You might end up with a very different scenario, but one quite well-suited to the dark, twisty tone of the book. Imagine Amy never escapes from her luxurious prison at ex-lover Desi's (Neil Patrick Harris) house, and Nick goes up the creek for her murder. We can picture the haunting final shot now: Nick, broken and gaunt in a prison jumpsuit; Amy, trapped in the posh cage where she's being kept like a pet parakeet.

The Keyzer Soze Approach

Another alternate scenario: moments after the big reunion between Nick and Amy, they disappear into the house and close the door behind them. BOOM, the house explodes in a ball of fire. As onlookers rush to gawp at the wreckage, Nick's twin sister Margo (Carrie Coon) quietly steps out of the crowd and walks in the other direction... Then whips off her wig to reveal that she is Nick! Sure it's crazy, but it still makes only a little less sense than the ending of "Fight Club."

Make The Baby Evil

The problem with all these theories is the suspension of disbelief required to buy that any ordinary human being could outsmart Amazing Amy, who is basically the Hannibal Lecter of the housewife world. But if she ever had a blind (or soft) spot, it would have to be for her own kid. In this scenario, that kid would obviously turn out to be either a) the titular character from "We Need to Talk About Kevin;" or b) the actual Devil. It's a win-win either way.

"Gone Girl" hits theaters October 3, 2014.