I've finished about seven pages of the script. The problem is that they're three separate scenes that only connect in my mind at this time. That's okay. I have a sense of where things are going. I recently rented the horror film Shallow Ground; one thing I liked in that film was the fact that you didn't really know what was going on until almost an hour in. All of the horror scenes worked better because there was a bit of a mystery to it that just isn't there in the average genre picture. It kept the audience off-balance. Actually Rosemary's Baby is the same way- you have an idea of what's going on, but not really who's involved or why.
So, I think that I'm going to try to keep the central conceit a mystery for at least the first half of the script. The next scene that I'm posting hints at it, but I want the story to be confusing as all hell breaks loose.