Assigned to spend the night shift with a Los Angeles fire station, television reporter Angela Vidal and her cameraman, go out on a routine 911 call. It takes them to a small apartment building where they find police officers already on the scene in response to blood curdling screams. Something unknown has infected a woman living in the building. After a few of the residents are viciously attacked, the residents of the building, along with the news crew, find that the CDC has quarantined the building. All outside information access has been cut-off, and officials are not relaying information to those locked inside. When the quarantine is finally lifted, the only evidence of what took place is the news crew's videotape.