Violent flu-like symptoms strike down men in the college town of Fort Collins, Colorado. Then, an elderly woman who just returned from China is rushed to a Northern Virginia hospital. Has this woman brought a terrifying disease to US soil?

After a huge earthquake hits California, a deadly fever is spreading quickly, and it's likely caused by a fungus released by the earthquake. Then in another story, a horrendous bacterial outbreak forces one of the largest food recalls in U.S. history.

Hundreds of injured soldiers returning from the Middle East bring back incredibly powerful mutant bacteria. Also, the CDC is flooded with reports of severe illness in children across the country - an invisible assassin is on nationwide killing spree.