A late-night television reporter and her cameraman tag along with a fire crew on a routine call to a Barcelona apartment block, hoping for colorful footage of the graveyard shift. Then the building is sealed from outside by the authorities, a resident turns violent, and a rapidly spreading infection traps everyone in the stairwells with something no longer human. Jaume Balagueró and Paco Plaza shoot entirely through the trembling lens of the news camera, turning found-footage horror into a relentless, breathless descent. Claustrophobic and pitiless, it earns its scares honestly, tightening dread floor by floor toward a truly nightmarish attic.