Season 2

Seven-year-old Kyle Lewis loves summer, then he develops a headache and a high fever, so his parents bring him to the hospital; doctors race to find out what is wrong with Kyle in time to save him.

A few days after the death of Dr. Autumn Klein, a doctor checks her chart to help solve the mystery of what killed her.

After patients present with similar symptoms, doctors have to act fast if they hope to save lives.

In Springfield, Mo., 61-year-old musician Mark Staudte dies suddenly, then his 26-year-old son, Shaun, dies five months later; Sarah, 24, falls ill nine months after her brother's death and is hospitalized in critical condition.

Physicians discover a strange, genetic disease that causes progressive neurological deterioration in children.

On Sept. 29, 1982, seven unsuspecting Chicago-area residents are stricken, and then die under mysterious medical circumstances. When the actual cause of death was discovered, a task force was formed to investigate.