The team creates a model of the virus causing an epidemic to better understand how it behaves and affects human cells. The novel virus changes continually, so it is difficult for them to create a vaccine.
A worldwide epidemic starts when humans cut down trees in an area inhabited by bats, forcing them to relocate. One bat carrying the virus dropped a piece of banana into a pig pen. One pig consumed the banana piece, and when it was slaughtered, the virus spread to the butcher's hands. The butcher did not wash his hands before he went to shake the hand of a guest, thus spreading the disease to the guest, who then spread it to other people.
The Eds are trying to sell ice cream to the other kids in the cul-de-sac, but no one appears to be around. They ring Jimmy's doorbell to see if he is home, and they are surprised to see that he has chicken pox. The Eds notice quarantine signs in front of everyone's house, meaning that they are the only ones who did not fall victim to the disease.