I'm a psychologist, but I was at least an hour or more into this film before I realized what was actually going on. The basis for the plot is sound and very imaginative. The execution is superb. It sort of reminded me of "Jacob's Ladder." When the truth is known, everything fits. The intelligent viewer will experience that 'of course' moment when the light goes on and everything makes perfect sense. Hawkes squeezes every bit of tension and fear out of the situation, and his characters are spot on in their reactions to impending doom. Great movie.