Hot News: 5 Things to Know About Gone Girl Author Gillian Flynn

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@michelletauber

10/03/2014 AT 10:50 AM EDT

Plenty of moms-to-be go into nesting mode, busily readying the nursery, stocking up on diapers and packing the hospital bag.

Then there's Gillian Flynn.

The author of the 2012 best-selling thriller - she also wrote the screenplay for the big-screen adaptation, in theaters Friday - spent the weeks before daughter Veronica June's Aug. 6 birth diving into an adaptation of the British crime thriller series Utopia.

'That's what I was working on right up until the baby came!' Flynn, 43, tells PEOPLE of the project, which re-teams her with Gone Girl director David Fincher. 'There's nothing lovelier than having a newborn and still plotting a dark conspiracy.'

Here's what else you need to know about the author-turned-Hollywood-power-player:

1. She was a newlywed and a new mom while writing Gone Girl. Married for six years to attorney Brett Nolan, she began writing her mega-seller while the two were still newlyweds - and expecting their son Flynn, now 4. Intrigued by real-life crime stories, 'I was very interested in what happens to the husband when his wife goes missing, and how quickly they can be turned into heroes and villains,' she says of unspooling her fictional tale of married couple Nick and Amy Dunne.

In her own life, 'I was not always someone who wanted to get married or thought I would get married, so being a true writer, I was always navel-gazing: 'What are good marriages? What are bad marriages?' So those two different things came together quite nicely.'

2. Her husband took the book in stride. Gone Girl portrays marriage in a decidedly dark light, and Flynn gave a copy of her manuscript to her husband before sending it to the publisher in case there was anything that hit too close to home.

'He just started laughing at me and said, 'Well, it all hits too close to home. Isn't that the point? It hits too close to home for everyone. That's where it works,' ' she recalls. 'I knew then I was in a good place with the book. I joke around about him being the muse for the most toxic marriage in the world, because if I'd been married to a less secure man, it wouldn't have gotten written.'

3. She wrote scenes in Gone Girl with David Fincher in mind. 'I was just writing in my basement and picturing it through Fincher's lens,' says the former Entertainment Weekly writer. 'The shopping mall scene, I remember seeing it just the way Fincher would light it. So when he came aboard, I kind of just wanted to punch myself in the face. It was all too lucky.'

4. Her second novel, 2009's Dark Places, is also headed for the big screen. A mystery involving Satanic cult hysteria in the 1980s, it stars Charlize Theron and will hit theaters next year. 'Charlize was kind enough to apologize to me that she didn't look enough like the character in the book,' Flynn says. 'I was like, 'You know what? I think we're going to be just fine.' ' Also in the works: a TV version of her 2006 crime novel Sharp Objects, 'probably a one-season series like True Detective,' she says.

5. She's buddies with Ben Affleck.As the under-suspicion husband in Gone Girl, 'there's so many angles you have to play,' Flynn says of Affleck. 'You have to believe that this is somebody who could have murdered his wife, and yet you have to hold this real affection and fondness for him because you don't want the audience to be completely alienated from him. You want them to be torn about it. I knew he had that ability. He has the skill as an actor to be completely off-putting and arrogant, but at the same time, he's just a cool guy to hang out with. He's like, 'We should go get a burger!' '

For more on Gillian Flynn and Gone Girl star Rosamund Pike, pick up this week's issue of PEOPLE

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