'Gone Girl' Writer Reveals Which Character She Most Regretted Cutting

'Cut' as in edit out. Not like stab-stab.

As the author of a book being adapted into a movie, Gillian Flynn had the rare privilege of writing the screenplay for "Gone Girl," but with those duties also came the responsibility of trimming the novel down.

Flynn worked with director David Fincher through the later stages of the scripts development, and even though she knew that the "Se7en" director could pull off a runtime longer than 90 minutes, there were going to have to be some cuts.

"In the process of writing the screenplay, [Fincher] said, 'We're going to blow it up and then winnow it back down,'" Flynn told MTV News over the phone. "The same guy [who] wants 30 takes from his actors is the same who wants to see every option for the screenplay. Then we set out to get it back down to size."

The result is streamlined, while completely maintaining the spirit and wicked humor of the book, but Flynn admits that not every darling she was forced to kill went down easy.

"There were certain characters in the book that I loved that served very little purpose, except for being interesting, quirky cul-de-sacs that I just knew from the beginning weren't going to make it," Flynn said.

The character the author misses most fits that bill of entertaining — if superfluous — asides exactly. "I always loved Desi Collings' mom," Flynn said. "That was the thing. Everyone loves. Everyone remembers her. She's in the book for all of four pages. I've always heard comments about her."

The mother of Neil Patrick Harris' character in the movie exists in the book to help establish the fragile, upper-class life of Amy's high school boyfriend. She's exactly the kind of shaky support structure you'd expect, and that's ultimately why she was left out.

"I knew from the beginning. She wasn't even in the first draft," Flynn said. "As David reassured me, he said, 'Don't worry. The second you meet Desi Collings, you know there's a mother somewhere. We don't necessarily have to see her.' "

"Gone Girl" opens in theaters on October 3.