Earlier this year, the Netflix film Bird Box became a pop culture phenomenon. That definitely wasn't something Josh Malerman, who wrote the 2014 book of the same name, expected—and he certainly didn't expect his novel to hit bestseller lists out of the deal. With a new novel, Inspection, coming out from Del Rey on March 19, PW spoke with Malerman about his new book, his old one, and what it was like to watch Sandra Bullock star in his story.

What was the process of having a book optioned for film like for you?

All while I was rewriting the novel, my manager, Ryan Lewis, kept telling me that he believed he was going to get the book optioned for film. I had no real reason to believe him other than that he’s a charismatic, brilliant dude whose ideas are off the charts. So I kept rewriting and he kept saying this will happen and then my agent shopped the book, it got picked up by HarperCollins, and Ryan got it optioned months later. So, for me, it was more than just the astonishment of getting my first book optioned for film—it was discovering what Ryan can do and how he does it. Universal optioned the book and Netflix bought it from them some time later, as the producer, Scott Stuber, moved from one place to the other.

What are the major differences between your novel and the Netflix adaptation? What are your thoughts on Netflix's changes? Did you have any input?

The biggest differences would probably be Tom’s role. In the book, the creatures[—supernatural entities that cause those who see them to take their own lives—]can get inside. And they aren’t necessarily [in the shape of] your “biggest fears.” But, truly, the movie follows the rules of the book, and I was pretty much crying at the very first scene, seeing Malorie tell the kids about the river trip, just the way the book opened. I didn’t have any say in the movie and I was (and am) fine with that. It was liberating, in a way, to hand off the book and see what other people could do with it. Because even if I had 100% control of the movie, it wouldn’t be the book. You know?

What was your favorite part of the film—perhaps a scene in your book you feel the film handled with exceptional grace?

So I loved this one scene that was in the movie but wasn’t in the book. It’s when Malorie intimates that she’s going to make Girl look, open her eyes, when they’re approaching the rapids. I got the chills at that part and I’m still not convinced I didn’t want to see Girl look! I saw Eric (the screenwriter) afterward and I asked him if that scene could be retroactively added to the book, because it’s the peak of the movie and it’s just fantastic.

Did you expect an audience reaction like the one Bird Box received? Were you surprised? Why do you think the story resonated with so many people?

I don’t think it’s possible to be prepared for what happened with this movie. I don’t think Sandra Bullock could’ve been prepared for that. None of us could’ve. And the reason I think it resonated so widely is because, first off, Sandra Bullock as Malorie was incredible, Trevonte Rhodes as Tom, too, and because the movie, like the book, acts as a Rorschach test. What do you see here? What do you think the creatures are? It’s almost like audience participation without the cheesy on-stage invite.

What's one thing that happened in your life after the film's success that's particularly memorable?

Bird Box reaching #4 on the New York Times bestseller list is pretty wild. I wrote the rough draft in 2006 and rewrote it in a big way in 2010, and it came out in 2014. So you can imagine how surreal this is, having been with these characters for so long, to see them in the public consciousness now. But there are more subtle things that are memorable, too, like just thinking about it all when I wake up and feeling warm, feeling like Bird Box is a friend of mine who’s done really well for herself.

How did you hear that Bird Box hit the bestseller lists?

I was driving home from Michigan’s Upper Peninsula and we’d reached an ice storm–induced traffic jam. My agent called to talk about other things and while we were on the phone, she received an email notification that the book made the list. She screamed in my ear and I probably did the same.

Are you working on any sequel to Bird Box? Do you plan to, if no?

Not sure yet. I must say, at the conclusion of the movie, I thought to myself, “Man. What happens to her next? I wanna know.”

What can you tell us about your next book?

Inspection comes out March 19. Soon. It’s about a pair of megalomaniacs who attempt an experiment that’s supposed to last a lifetime, but goes horribly, violently wrong long before then. It’s a gender equality anthem. It’s a book about closing the door on nature and watching it squeeze itself out the window instead.