People in Ocala, a small city in Florida, face an epidemic of sudden blindness. The head of Ocala Regional Medical Center's emergency room, David Belmont, and his wife, Sarah, a high school science teacher, seek answers to what is causing the blindness, where did the blindness originate and why did it suddenly afflict people and animals without warning or other symptoms? Their son, a high school senior, is one of the victims. These questions are baffling an experienced investigative medical team from CDC whom arrive later in the day from Atlanta, Georgia. Unbeknownst to David, Sarah and the leader of the CDC's team, Russell Patton, has a mutual amorous secret.