The new horror movie The Purge is built around a remarkable image: a cookie-cutter mansion is transformed into a fortress, with steel blockades over all the doors and windows, so a well-to-do American family can ignore the wave of horrible violence passing through their gated community. It’s the sort of image that studio filmmaking is so good at creating, rich in associations and unmarried to any clear political ideology. The mansion-fortress alternately suggests a metaphor for American isolationism, fear of terrorist attacks, the lucrative security industry, and our culture’s fascination with self-defense. (And then there are times when it suggests nothing at all, asserting the inexplicable authority of something out of a dream. If René Magritte were alive today, The Purge might be his favorite film of 2013.) Seeing that the premise offers such a variety of interpretations, I’m not surprised that The Purge was this weekend’s number one box office attraction—it’s got something for everybody.