Four veteran teachers join together to try and find the source of the illnesses, but are met with resistance at every turn. Finally, after enlisting the help of one of their former students-nine-year-old Jonathon, and his grandfather, who drives the school bus-the teachers are able to get closer to the truth.
The carefully hidden secret they discover is so shocking in its far-reaching effects throughout the country, that the magnitude of it leaves the teachers shocked and emotionally shaken. Because the situation is dangerous, the teachers agonize over asking little Jonathon to go back one last time to gather more information. Time is of the essence as more children around the country are exposed to danger.