What’s in the box? There almost wasn’t going to be a box.

Easily the most memorable thing about Se7en, a film full of memorable moments, is the shocking finale, wherein it’s revealed that John Doe has cut off the head of Detective Mills’ wife and put it in a shipping box. Who could ever forget the look of total despair on Brad Pitt’s face in the moments before he pulled the trigger, giving in and completing John Doe’s ultimate masterpiece?

But once upon a time, that ending was almost excised from the film.

As writer Andrew Kevin Walker just explained to The Hollywood Reporter, the original director of Se7en was going to be Jeremiah Chechik, who made his directorial debut a decade prior with National Lampoon’s Christmas Vacation. Yes, the director of the most beloved holiday movie of all time almost directed one of the most disturbing thrillers of all time. Who knew?!

When Chechik came on board, he asked Walker to rewrite the ending, which in this iteration of the project was going to be set inside a burnt-out church. There would’ve been no box and no head in a box, which needless to say would’ve completely changed the movie. Of course, Chechik ended up leaving the project, and a mix-up resulted in the original script coming back into play.

As it turns out, the original version of the script accidentally ended up on David Fincher’s desk, and he agreed to direct the film only if that original ending remained intact.

Andrew Kevin Walker explained how everything worked out perfectly:

As a writer, when you come on a project and you don’t see eye to eye with the director … you have to make a choice whether you are going to stick around and rewrite stuff or perhaps feel like you are ruining your own material. That said, had I told Jeremiah Chechik during the process of rewriting Se7en, ‘You know what, I don’t really agree with getting rid of this stuff and changing the ending and setting it in a kind of burnt out church, and getting rid of the head in the box, etc. So I quit.’ If I had done that, I wouldn’t have been around for the happenstance, luck, fate of Fincher receiving the wrong script. He might have gotten my script, but it would have been at least one, maybe several writers down the line, and he probably would have proceeded with those other writers

On a related note, Walker just shared the original draft of Se7en for the first time!