NEW YORK — Secrets are big business in Hollywood. Letting spoilers get out about your upcoming movie or a TV series can impact whether people actually watch and/or diminish interest in buying tickets. So it's no surprise that even with movies based on popular novels like "Gone Girl," where all the secrets can easily be found in print, everyone involved is trying to keep things quiet. Even if the film's plot might not be that different than the book.

Both Ben Affleck and Carrie Coon, who play twins Nick and Margo Dunne in "Gone Girl," are no strangers to keeping secrets. Coon earned raves on the HBO series "The Leftovers," a show that hinges on an unexplained phenomenon, and Affleck just happens to be in this little blockbuster "Batman v Superman: Dawn of Justice" that won't even hit theaters for another year and a half. For those of us who can barely keep secrets in our immediate family, how do they handle months of pestering from fans and friends alike?

"You work so hard on [the project] you don't want to talk about it anymore," Coon says in the interview above.

Adds Affleck, "They keep secrets from the actors because they know the actors talk. And they give you stern lectures about, like. 'This is important. You need to shut your mouth!' They are going to be very mad at you if you give this away.' You're encouraged to keep secrets. In this case, it is a book. So, it's sort of like 'Game of Thrones' in that way. If you really want to know the spoilers, if you really want to know what happens, you can go and read the book. If you want to be surprised, you don't. So they kind of exist simultaneously. With 'The Leftovers' I think it's different because I want to know what the [expletive] is going on."

"I would love to know," Coon insists.

"On the TV shows they keep the actors in the dark," Affleck says.

"They do and I really like ambiguity in art and so even as an artist, even as an actor I don't always ask all those questions," Coon reveals. "I make up my own answers and if it's different than who is making it, that makes for an interesting conflict and some more interesting stuff happens on camera that way."

One secret that the cast are inadvertently letting out is about the film's iconic director, David Fincher. The man behind "Se7en" and "The Social Network" has tried to limit his conversations with the press over the years, which has given him, it appears, an unjustified reputation.

"He's actually a nice guy," Affleck says. "I thought he was going to be Prince of Darkness, whip-cracking, obsessed with the serial killers, but he's actually very witty, charming. He's guarded, I think, so he doesn't project that to the press because he's been burned and he's very suspicious, but he's a lovely, lovely man. 'You're a nice guy? You're David Fincher! You can't be a nice guy!'"

Well, you can't keep everything a secret forever.

For more on Coon and Affleck's thoughts on working with Fincher and "Gone Girl" watch the video embedded at the top of this post.

"Gone Girl" opens nationwide on Friday.

With over a decade of experience in the movie industry, Ellwood survived working for two major studios and has written for Variety, MSN and the LA Times. A co-founder of HitFix, Ellwood spends his time relaxing hitting 3’s on the basketball court and following his beloved Clippers.