3 women living in vastly different locales have one thing in common: they've become unwitting hosts to baffling and deadly terrors. A teenage girl thinks she might be losing her mind, but she soon realized has a life threatening inflammation of the brain.

When three unsuspecting young families are thrown into a tailspin, they are shocked to learn of the tiny culprits wreaking havoc on their lives. First, a married couple in California watch helplessly as their son struggles for every last breath.

A Massachusetts EMT is shattered by a routine emergency call when she discovers that the victim is her son. A self-described tough guy in New Jersey is reduced to tears when something sinister starts to rip apart his intestines.

Disaster befalls three individuals who are suddenly living their worst nightmares. A contractor suffers a bump on his head while he is working, but days later, he finds himself in the ICU fighting for his life with something in his brain.

The lives of three young people are suddenly turned upside down. In South Dakota, what begins as a common sore throat quickly spirals out of control for a fifteen year old girl, as a rare and dangerous affliction leaves her clinging to life.

A war veteran, a PhD scientist, and a newborn, all clinging to life by a string. In Tennessee, new parents are horrified when a deadly infection pushes their baby daughter to the brink of death.

Christmas time is here, and these three victims each receive a monstrous gift. In Florida, a woman is out Christmas shopping when she suddenly feels a stabbing pain in her eye so severe that she believes she sees shadows of worms in her eye.

Trouble is lurking in the bodies of three different women. In rural Washington State, a teenager's shoulder pain leads her to being quarantined in a matter of days. If doctors can't determine what's attacking her, she'll die.

Three lively people suddenly come face to face with their own mortality. In Virginia, a teen suffers seizures and sudden blindness, when doctors discover her brain is under attack.

Three healthy people with a love of the outdoors are struck down by a deadly menace that lurks inside them. In Ohio, a young boy wastes away in front of his parents' eyes as a mysterious infection overtakes his body.

Stories of people who have contracted and survived rare and deadly diseases, infections, or parasites.