Canadian doctors are alarmed when a middle-aged woman dies of cryptococcal meningitis in 1999. Over the next few years, doctors see dozens of similar infections with pneumonia-like symptoms including shortness of breath, weight loss and severe headaches. Vancouver Island becomes home to the largest outbreak of the deadly fungus anywhere in the world.

In 1993, aquatic researcher Joanne Burkholder suffers an array of troubling symptoms while working in her North Carolina State University lab. A fellow researcher confides that he has recently been plagued by bizarre medical problems including memory loss, confusion, numbness and a burning sensation on the skin, symptoms identical to Burkholder's.

When an unpredictable germ terrifies Texas in 1998, the CDC and health officials alert all neighboring states and territories to be on the lookout for streptococcus outbreak, the same bacteria that causes strep throat. This new strain, however, will kill 33 people, causing flesh-eating viruses, introducing deadly toxins into the blood and introducing pneumonia.

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.

Phil Rouss realizes a lifelong dream when he opens an antique auto restoration business with his long-time friend Steve White. They divide the work - Rouss will restore the cars and Steve will handle the books. The business is an immediate success, but within weeks Rouss is struck down with a mysterious illness.

Robert Curley is newly married and is renovating an old home for he and his wife, Joann. He is also an electrician doing repair work in a local chemistry lab. Within weeks of starting the new projects he becomes violently ill. His feet and hands tingle for no apparent reason. Doctors diagnosis his ailment and send him home with medication, but that doesn't work.