Diagnosis: Unknown

Outside of Roanoke, Virginia, health officials scramble to find the origin of a deadly bacterial outbreak of pneumonia.

Health officials in Albuquerque, New Mexico face an outbreak of a rare and fatal blood disorder. Patients suffer sharp muscular pain, fatigue, fever and rashes. Twenty-one people die from the illness. Five other states report similar cases. The epidemic is spreading. The Center for Disease Control assists federal and state health officials in their hunt for the cause.

In late August of 1999, an infectious disease specialist in Queens, New York reports that she has two elderly patients with neurological disorders. More cases crop up in the following days, several patients die. Initial tests confirm that New York has been hit by an outbreak of the mosquito-borne illness, St. Louis encephalitis. Nearly a month later, exotic birds begin to die at the Bronx Zoo.

In August of 1998, Marilyn Miller is awakened by her son's frightened cries. She finds him suffering from a dangerously high fever and severe abdominal pains. As doctors work to stabilize him, she begins to feel the sickening symptoms herself. Doctor's suspect a food poisoning outbreak and direct her to call the Minnesota Department of Health.

On the tiny resort island of Martha's Vineyard, landscaper, Patrick Ryer, suffers from chills and high fever. Patrick has contracted Tularemia, a rare bacterial disease. Health officials alert residents and tourists who crowd the Vineyard over the summer holiday. Over the next month, ten more people are diagnosed with the disease, including other landscapers and children.

A hospital in Walkerton, Ontario is flooded with patients with the same alarming symptoms. All suffer from fever, nausea and gastrointestinal problems. Health officials suspect water contamination, but the Public Utilities Commission (PUC) reports that the water is safe. The next day, 20 more patients are admitted with the same symptoms.

A classic case of Munchausen Syndrome by Proxy, Genene Jones killed at least 47 patients with the muscle relaxant succinylcholine while working at Bexar Medical Center in Texas. She loved creating emergencies, the excitement of a ""code blue"" and especially the reactions of family members when told of the death of a loved one.

Nine hundred children are sent home from school and thousands inoculated during an outbreak in Massachusetts that depletes local supplies of antibiotics and lands four middle school students in the hospital. Ten-year-old Kayla St. Pierre spends ten days in critical care and loses all of her fingers and both legs to the disease.

An unassuming male nurse from Kentucky comes under scrutiny when hospital officials notice that death is unusually prominent during his work shifts. In fact, death seemed to follow Donald Harvey from job to job, beginning in 1970 and ending with his arrest in 1987.

Dr. Harold ""Fred"" Shipman was known as a dedicated, hardworking and community-minded doctor who spent his life gaining the trust of his patients and the respect of his colleagues. And for 25 years, nobody suspected that the town doctor was amassing a death toll that would make him one of history's most prolific serial killers.

Reverend Dwight Moore is at death's door when he is transferred from his local hospital to Memorial Hospital in Chapel Hill. With all the expertise and technology of modern medicine at their disposal, doctors are still unable to find of the cause of Moore's symptoms, which include stomach pain, numbness, and hallucinations.

In an exclusive Kansas City suburb, cardiologist Mike Farrar is suddenly stricken with a powerful and mysterious stomach illness. The violent and terrifying symptoms are relentless, leaving the man fighting for his life. Mike's doctors fight to save him, but they struggle to find the source of the disease that is making him waste away before their eyes.