I agree Em. As an actor and director, I can tell you that the audience ABSOLUTEY hates that kind of film. The only time it "sort of " works is when the antagonist is a demon or ghost. Even then, the audience feels ripped off if it doesn't manifest somehow (appearing in smoke, shadow etc..). There was one good film "FALLEN" (1998 with Denzel Washington and John Goodman). Here it was a demon and it got away, but the audience still saw it move around the film and take over characters (Great rental btw: )