I was hooked from beginning to end. Great horror comes from disturbing imagery and organic shocks that are created not to make you jump, but to make you go "What the f*ck did I just see?" All the other commentators gave short summaries of what the film is about, so I won't rehash what has already been said. I was telling other people about this movie days after I had seen it just because it still haunted me. I even had a bad dream after seeing it, and I am a true horror fan, not easily spooked by tripe like "The Grudge" or even "Silent Hill". What gave me the bad dreams was the unease I felt about what I would do if I were in that cell with those guys. What would my personal horror be? my subconscious took me there, and it was not pleasant. That my friends is what a good horror flick does to you! The best part of this movie is that it is subtle. It's not about Bogeymen that jump out at you,alien invasions, or tons of gore. It's the opposite. The horror you create in your own mind. The irony for the four characters is that the horror comes not from an external force that asserts it's power over them. Simply, the men ask for the one thing they desire, and they get it...but not in the way they imagined. So on the one hand, they get what they wish for from an occult book, but may ultimately wish they hadn't. Sometimes being locked in a jail cell is the best place to be!