There was once a small city called Osdale. It was a peaceful place where classes defined everything. Rich vs. Poor, you know the drill. One day there was an epidemic, a disease that didn't care what class anyone came from. This disease made even the calmest man attack his own flesh and blood. The disease caused anyone who was infected to become enraged at random intervals of time. One day the rich decided to ban together and leave, they offered a price for anyone else who wanted to leave. Those who couldn't pay, were left behind. So the people who could afford their freedom left. This left behind hundreds of people and one disease. The ones who had left the city thought that the disease would be dangerous if it spread, so they lied to the government, by not telling them about the others left behind, and the city was closed off from the outer world. The escapees figured that everyone would sooner or later die...

They were wrong.