If you are looking for a thriller with lots of gross-out gore or shockers, this is not for you. If you want some cerebral film that leaves you pondering life or thinking deeply about something, this is not for you. If you want sheer entertainment, see this film! If you are looking for an engrossing, suspenseful thriller that keeps you completely on edge of your seat, yet does not give you a horrible nightmares, this is for you. There is violence and blood but not as bad as expected. And the sequences flashing forward and backward in time but were not confusing. I usually don’t like that, but this was easy because you stayed in one period for a long time, long enough to get attached and connected. There are points of action that wouldn’t go so smoothly in reality but it’s thrilling enough to suspend disbelief. For the critics who object that you never see the “monster” please realize the monsters are in your own head. This film artfully leaves the true fear to your own imagination. So glad I watched it!