It begins with no clear warning. It seems to come out of nowhere. In a matter of minutes, episodes of strange, chilling deaths that defy reason and boggle the mind in their shocking destructiveness, erupt in major American cities. What is causing this sudden, total breakdown of human behavior? Is it some kind of new terrorist attack, an experiment gone wrong, a diabolical toxic weapon, an out-of-control virus? Is it being transmitted by air, by water.. how?