That is literally the synopsis that I found. Does the synopsis really matter for these movies at this point. If you are into them - you know the deal. If not - why would you start with number four?
I have really enjoyed this franchise until this point. The first one scared the living hell out of me. The second one was very creepy. The third one (a prequel) backtracked a little but still had more than it's fair share of creep out moments. This one was more of a sequel to part 2 and started off with great promise, but for the first time I wasn't scared. I didn't find myself dreading what was going to happen. I didn't find myself jumping. It was basically a 90 minute set up to the final scene that actually made the story movie forward ever so slightly.
Again - whether I recommend it or not doesn't really matter. If you saw the others and liked them - you will see this one. If you didn't - then you probably won't.
