I get your point, but I guess what I'm trying to say is that, at least to me, this book didn't feel like a mystery. It felt somewhat like a horror story, something like The Turn of The Screw. I'm not saying i thought there were ghosts involved, just that the tone was very horror-like, and that their situation was, to me, a manifestation of their collective internal guilt.

I think that's why the epilogue was such a betrayal to me.