A group of students arrives in a small town during a hiking expedition. Once there, the local priest accuses them of being communist agitators on the run from an army crack-down against student demonstrations in nearby Mexico City and rallies the townsfolk to lynch them. Based on a true story.

When a worker is found murdered on the construction side, the investigation swiftly turns from things criminal to the political circumstances surrounding the building itself. Widespread corruption and neglect by the builder himself are seen to have brought the situation about. Much of the movie is filmed using hand-held cameras, and the majority of the dialogue is in the difficult-to-understand and very slangy Spanish dialect of Mexico City's bricklayers.

After the death of her abusive husband, Matilde finds her new best friend in Miguel, her young, insecure, and disoriented neighbor.