The end of the world wasn't planned, but everyone saw it coming. All of humanity had heard the news reports and stories about the polution we, as a species, were inflicting on the world, but we simply turned away and ignored it. And then it tapped our shoulder and showed us what a huge mistake we had made. Disease running rampant, air quality dwindiling, and still people saw this as an opportunity to make money. In a rush to save humanity, scientist developed a purification system to clean the air and called them Nets. These Nets were set up around large city's, and things were good. But the nets couldn't cover everything, and eventually city's began to overpopulate. It was decided that only people that could pay could stay, and everyone not rich enough to pay the taxes on life were shoved back outside and into the Background. This is what becomes of humanity.
Season 4 of The Virus Within
Trinity is familiar with zombies, being one herself, but when strange zombies start appearing, she realizes that the world she knew might be changing yet again.
When a dangerous set of scientific notes are discovered, Trinity and her friends don't realize anything is wrong until a frantic radio call comes in. Unaware of the notes, they race to the south and struggle to determine where the strange zombies came from. The zombies are unlike any ranks previously seen, and they aren't as predictable. Some have new tricks hidden up sleeves, forcing any Stronghold they encounter to quickly adapt to the new challenge or risk being overrun. Secrets never remain hidden, and zombie apocalypses never make life easy.