2008’s Cloverfield was a cultural reset for horror films. A frantic found-footage flick following a group of friends whose farewell party is crashed by a Godzilla-esque monster rampaging through New York City, Cloverfield became an instant hit with audiences—at least those without motion sickness.

With the film’s rampant success (and several spin-offs), it’s hard to believe that behind the scenes, Cloverfield’s creation was just as chaotic as the movie itself.

“At the time, it was definitely an adrenaline rush because, honestly, I didn’t know if it was going to work. I felt like I was doing this high wire act and was thrown out into this craziness going like, ‘Well, gee, we have no idea if we can make this handycam VFX movie, [or] if anyone’s going to want to see this,'” director Matt Reeves told ScreenRant in a recent interview, detailing how his friend (and the film’s producer) J.J. Abrams pulled him into the Cloverfield project just weeks before shooting began.

And, as Reeves really stresses, there was no script when he signed on to the sci-fi horror—leaving the Batman director, Abrams, and screenwriter Drew Goddard scrambling to put one together in less than twelve weeks.

“We didn’t have a script when we started. Drew had this outline, but I remember J.J. specifically said to me, ‘Look, it’d be really cool if you did this,’ and I said, ‘Well, why don’t I wait til we have the script, so that way I can see?’ and he said, ‘No, no, no, you don’t understand. We’re shooting in 12 weeks.’

…Drew Goddard wrote a wonderful script that we had ready and done, but it was done literally two weeks before we were shooting. So, it was crazy,” the filmmaker added.