Watching this movie, anyone can tell that two people directed it. Also, that both had something different in mind when they were doing it. Fulci I believe was going for supernatural zombies and Mattei went for the strange chemical that turns people into zombies like in his "Hell of the Living Dead". I also think he saw "Return of the Living Dead", because some of the scenes in this one will make you think about that one. In the end Mattei's storyline is the one that is the dominate one, mainly because he did the editing. It probably would have been better if Fulci finished it, but I think he quit because it just was not up to his standards. The results, a terrorist for no reason steals a dangerous chemical that turns people into zombies and the army tries to cover it up while a bunch of people at a hotel try to survive. Once again this is not what I believe Fulci intended, I think he was going for a plot more similar to "The Beyond", but what we see on screen is another evil army cover-up movie.
