There are two books I have read in my brief life that truly frightened me. One is The Tailypo: A Ghost Story by Joanna C. Galdone, which I read in the third grade (scared the absolute crud out of eight-year-old Me, and even still makes me uneasy when I think about that evil little creature watching that man from the foot of his bed in the dark). The other is Hostage to the Devil: The Possession and Exorcism of Five Contemporary Americans by Malachi Martin.
Whether or not you are a skeptic in demonic matters, this book will probably still send chills up your spine. It's already given me one virtually sleepless night. Martin chronicles the cases of five individuals possessed by evil spirits, including their histories, the histories of their exorcists, and the circumstances as to how they became possessed. Each exorcism was tape recorded, so Martin's descriptions of the exorcisms should be relatively accurate. In my opinion, the two most disturbing cases in the book are The Virgin and the Girl-Fixer and Uncle Ponto and the Mushroom-Souper.
There is one passage from this book that has really stuck with me. In it, Martin and Father Mark (the exorcist in the "Uncle Ponto" case) are discussing the fate of exorcists:
It was a source of some amazement to [Mark's] close associates and superiors that he did not go the way of most exorcists. A few years' active ministry in exorcism, and the majority paled, as it were: they seemed to wither in a variety of ways; some by illness, others by premature aging; others still because they seemed to have lost the will to live.
"Most of us crawl away and die somewhere quietly," Mark said as we talked one evening. I knew he was right.
"Why not you, Mark?"
"Well, you see," Mark began jokingly, "I have this great pal upstairs, and when I start into one of those exorcism businesses, he comes along and holds my hand."
Overall, I found this to be better than a "good" read--it was a great read. You just might not want to read it after the sun has gone down.