Countdown from Earth

Winnie lives in a world where 95% of the population has been wiped out by a mysterious phenomenon. They can't call it a virus, because no one knows what it is. All that they know, is that one day, a wall appeared, with more timers than anyone has ever seen in one place.
One timer ended, and one life ended with it.
Stuck living in a small town with only a handful of people, Winnie has to figure out how to live out her timed life.
The one problem with the timers...no one knows which belongs to them.