The eleventh plague
One time in the book Stephen and his father encountered some hostile travelers holding people hostage and they were trying to rescue them, but as soon as the hostages were free they betrayed their Stephen and his dad and ran away with their supplies.
Another example of this theme in this story was when a group of people had camp set up, another large group of wealthy, well-supplied, and well-armed travelers showed up and offered to help them out. Just as the newcomers gained their trust they open fired on the entire camp, killing nearly everyone. The group then looted for supplies and left.
One day everything was normal and suddenly a war with china got out of hand and china destroyed most of the US civilization. On top of that China created a disease and sent it over to the US. The plague took out 2/3 of the nation. Leaving them with nothing, no government, no society, pure chaos, and pushed back to square 1.
Later on in the story, Stephen comes across a nice little civilization called settlers landing. The place was a high-class gated community that appeared to be untouched by the war. Just when he thought he had his life figured out, things took a turn for the worse at settlers landing. A simple prank was taken too seriously and a war broke out in Settlers Landing, wounding and killing many people. Most of the buildings were burnt down in the battle. Stephens world was turned upside down again.