If there’s a chill in “The Stranger”—and there is, a gray-blue, suffocating fog that seeps in under the doors and seeps, ultimately, into your bones—it is not the chill of intellectual rigor, or even of well-honed genre machinery. No, what Thomas M. Wright (whose name, one suspects, is stiflingly respectable but also suspiciously absent from the pantheon of directors who actually terrify us) gives us is a thriller so restrained in its horror, so unsure of its own human subjects, that it might have been devised by police proceduralists who, after a long day filling out forms, briefly remembered they had souls. “The Stranger” is heavy with atmosphere, but the air is so thick it deadens more than it haunts.