I remember reading it while staying at a bed and breakfast in Connecticut. I would leave the book outside on the veranda at night instead of on the night stand (it scared the h$ll out of me).;-)
Sum of All Fears by Clancy did that to me staying in a B&B in the UK.
Worth another read. Once you understand how he structures the book, you can skip the literally gory details and see the patterns. The important part of each incident is how it happens, and what happens to the exorcist in each case.
Each case is completely different in what leads to possession. He also picks two cases where priests were possessed. He picks a case involving perfect possession.
In the end, he shows what happens to the poor exorcist. Very uplifting, oddly enough, and does WONDERS for how you look at your relationship with God.