Something disturbing is going on in San Francisco each and every night. Certain locals who are out at night, are being set upon and slain, by someone or something, to be found in the morning mutilated or parts missing. Ocassionally they are never found at all ditto the parts that go missing. Tonight one teen is going to witness a massacre at the hands of this lethal mystery. And might be able to shed some light over it to the cops. That is if she survives the night.