Brainstorming
“If you get to the center, you won’t get Bill back” This clearly suggests that getting Bill back is a possibility.
Correct me if I’m wrong but the people who’ve died were all invited by Lee?
I think that Lee is behind it all. But she’s not killing them - they’re jumping.
The time she spent “missing” … she and Bill planned all of this. Bill didn’t die, he jumped.
So in this case, why is Lee creating this puzzle for Darby? What is she using Darby for?