The nastiest parts of the web are the focus of the new film American Sweatshop. It’s got one of the most unsettling, distressing, and downright scariest scenes of the year—and it’s not a horror movie.

One place the current crop of horror films is pushing boundaries is in the aura of dread and tension that oozes from scene after scene. While it’d be easy to just focus this piece on jump scares, the ...