Everyone is susceptible. Except, of course, those that disappeared over a year ago. Mostly those ranging between the age of 30-to-dying, and a few younger adults. Seemingly no one one earth now can get a disease.
But they all have The Virus. The tirelessly inexplicable, ever complicating disease that the now otherwise immune-to-all-sickness earth population is all catching. And no war, no plague, no unnatural dissaster could have possibly prepared us for all that came with it.
A zombie virus is released on the world, adults and children are torn apart indiscriminately as entire countries fall in chaos. A group of teenage students are at school when everything goes down and must fight for survival against all odds, surviving off nothing but hope and each other.