[REC]

Reporter Ángela Vidal and her cameraman Pablo are riding along with a Barcelona fire station for a late-night segment — an easy piece, human interest, firefighters waiting for calls that mostly don't come. A call comes in to a residential apartment building. They follow the crew inside.

An elderly woman has been found in a state of violent agitation in her apartment. She attacks the police officer who tries to approach her, biting through his throat. Before anyone can leave to report it or get help, the building is sealed from outside. Residents gather in the lobby frightened and hostile. A health official who enters and never explains himself says it may be a highly infectious parasitic agent affecting brain function. The infected move with a speed and ferocity that makes the quarantine's real function clear: containment, not rescue.

The building falls floor by floor. Infected residents multiply. The survivors retreat upward. A locked penthouse at the top belonged to a Vatican agent who had been attempting to isolate a biological basis for demonic possession — to find the organic mechanism behind the phenomenon so it could be treated, controlled, or transferred. His test subject, a young girl named Tristana Medeiros, is patient zero. She is somewhere above them in the dark.

The power fails. Pablo switches to the camera's night vision. They enter the penthouse. The agent's research surrounds them — evidence of years of work on something that should not have been worked on. Something moves in the dark at the edge of the image, drawn by sound. In the footage's final seconds Ángela is seized from behind by something large and malnourished and dragged screaming into the dark. The camera hits the floor. The recording ends.