Horror movies take place in their own territory. The trick is to get us there. It doesn't matter whether they start with fantastic premises and gothic settings, or with ordinary neighborhoods and daily experience, because the places and assumptions change when they enter and are redefined as horror territory—by the intrusion of crazy violence, for example, or an awful discovery: that the folks in the next apartment are Satanists or that a maniac made a bloody sandwich on the cutting board while you were out of the kitchen. The rules have changed, and it is dangerous to find out how they have changed and why It is also difficult. It can be hard to realize that one's friends are pods or that they have to be dismembered, hard to find the terms of a world that behaves like a slaughterhouse or a dream.

The world can fill up with angular, scary shadows, lurking with little monsters—or it can look the same but be different underneath. Different in a way you can't define, a perceptible but invisible tonal shift that is the ideal of one kind of horror film, a Peeping Tom or The Seventh Victim.