Part horror movie, part medical detective story, find out what happens when people fall prey to an infection from a parasite, those nasty microscopic creatures found in water, soil and even in the air. Victims' stories are retold, including how doctors and scientists attempt to unravel each case before it's too late. Biologist Dan Riskin, assisted by doctors and experts who witnessed each case, leads the scientific discussion about each parasite.

The lives of a young boy, his classmates and their gym teacher are shattered forever by the presence of a shooter in their small-town elementary school.