The original script was written by David O. Russell, who is no slouch. Some of [the rewrite] was just from a female standpoint and working with the character of Elizabeth. She is an incredible female hero and a great literary hero. To me, it made perfect sense that she would also fight zombies. I feel like they just needed a bit of that “girl perspective.” Some of [the rewrite] was just working with the third act. It’s always hard to land the third act of a movie like this. Every movie I have ever worked on you work and rework the third act until you are blue in the face.