There is no correct way to write a screenplay, but most writers like to have an inkling of where they’re going when they start tapping away at their keyboard. Not Cregger. According to an interview with The Hollywood Reporter in 2022, he wasn’t thinking about a concrete story, let alone which actors he’d like to cast. “I just wanted to write a scene,” he said. “So that double-booked Airbnb thing was just an exercise for me to play and have fun writing, in a way that a little kid colors with crayons.”

Cregger wasn’t flying completely blind. As he told THR:

“When I was writing the movie, Keith was a bad guy. I thought that’s where it was headed. And when Tess [Georgina Campbell] went downstairs with him, I was like, ‘Okay, whatever he is going to do, we should probably do it now.’ But then I just had this moment where I was like, ‘This sucks. Everyone is going to expect him to do something, but I can’t think of anything that would fulfill what our imagination is.’ I was out of gas. I was like, ‘I’m dead,” and I just stared at the screen.’”

Then the monster sprung from his imagination, and, well, he was dead again.