An ordinary day's hike gets rough when two youngsters escape from the main group into the woods and, after finding a grotto, discover that there is more to it than just darkness.
Residents of an enclosed neighborhood in the middle of Mexico DF are shocked by a violent crime, and for one resident in particular, young Alejandro, the drama is ratcheted up when he encounters the lone kid who escaped the event and is hiding out within the neighborhood's borders.
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.
