A Christmas baby is born, but doctors find her brain was infected in utero. A woman thinks a worm is in her eye, and a man gets a nasty surprise after surgery.

Three families are turned upside down by deadly monsters. A four-year-old boy is plagued by crippling pain. A college student with a small cut finds herself fighting for her life. A woman is driven to insanity by an intruder in her own body.

Monsters can hijack our bodies in any number of ways. A man breaks out in a mysterious painful rash. A woman experiences bouts of piercing pain in her throat. A teen girl is left debilitated by strange spells of dizziness and fatigue.

A family's cruise ship vacation turns into a living nightmare when their two year old swallows a sinister monster. A mother of two is plagued with a mysterious infection. Deadly parasites hijack the brain of a six-year-old boy.

A mysterious infection brings a tough football player to his knees. To her horror, a stay-at-home mom has parasites devouring her eyeball. And a marina dock master is attacked by sea creatures!

A baby falls mysteriously ill and struggles to breathe; a man has something living in an embarrassing place; a woman's weight gain confounds experts.

A boy getting sick, upchucks his own feces; teenager contracts horrifying disease; young girl's illness is undiagnosable, so she is quarantined.