A four-year-old Pennsylvania boy gets a runny nose with red discharge, stomach pains, pale skin and extreme pain from accidentally putting a button battery up his nose; an Idaho college student gets a cut on her knee, but then develops agonizing leg pain followed by septic shock from an Aeromonas hydrophila infection; a Pennsylvania woman has strange outbursts and appears to lose her mind from a teratoma growing on her ovary giving her Anti-NMDA receptor encephalitis.

During a family vacation cruise, a Louisiana 2-year-old is restless and drools, which leads to vomiting and kidney and liver failure due to abrin poisoning after accidentally eating a bead from a necklace made of the rosary pea plant on a trip to Jamaica; a California mother-of-two develops a bloated and descended stomach and colon, a body-wide rash, fluid in her abdomen and meningitis from valley fever caused by Coccidioides immitis; a 6-year-old boy suffers a headache, vomiting, blindness and bizarre neurological symptoms which include crossed eyes, that prove fatal. Only when it is too late is it discovered that he was infected with the Balamuthia mandrillaris amoeba.

A Canadian woman suffers a piercing pain in her throat and vomiting from accidentally swallowing a grill bristle (for which she thought was a sprig of rosemary) which got caught in her throat during a barbecue; an Arizona retired firefighter vacationing in Belize develops growing and eventually opening purple bumps on his limbs, lethargy, and hand pain from cutaneous leishmaniasis; a Nebraska 14-year-old girl is struck with swollen lymph nodes in her neck, dizziness, fatigue, blackouts, and body pain from Tularemia.

This episode looks back at three cases from past episodes: a teenage boy with a grill bristle in his intestines (A Deadly Swim); another teenage boy with leprosy (Help! My Son is a Leper); and a teenage girl whose lungs are afflicted with Cryptococcus gattii fungi (My Body Is Rotting).

A infant becomes totally paralyzed after accidental exposure to botulinum toxin; a Texas man develops severe pain in his scrotum for which doctors think is an ingrown hair, but it actually turns out to be botfly larvae which infected him while he urinated outdoors in Costa Rica; a Florida model/dentist is confounded by her mysterious weight gain, and over the course of a year she suffers continuing weight gain, blurry vision, crippling hand pain, and muscle weakness before it is discovered her breast implants are contaminated with Aspergillus fungi.

An Idaho 17-year-old football player is struck with a sore throat, breathing difficulties/lung pain, confusion, kidney failure and even tackles his own mother from Group A streptococcus bacteria infecting his blood; an Illinois mother of three kids develops an itchy eye which leads to face numbness, loss of depth perception and blindness as the result of an Acanthamoeba keratitis infection; a dockmaster develops crippling pain in his hand from a Mycobacterium marinum infection along with pimples on his palm from barnacles growing in his hand.

The show's fourth Christmas-themed episode, and the second episode of the series that looks back at three past cases, including: a baby whose brain was infected with Cytomegalovirus in utero (All I Got For Christmas Is Brain Surgery); a woman whose eye is infected with the worm Dirofilaria immitis (A Holiday in the Hospital); and a man who has a surgical sponge left in his colon (also A Holiday in the Hospital).