A girl sleeps for ten days in a row, but tests are normal and doctors are perplexed; a marathon runner experiences unexplainable fatigue.

A doctor makes an unexpected discovery when he operates on a young woman; doctors try to reach a diagnosis when a marathon runner experiences mysterious fatigue.

A man suffers from a series of debilitating symptoms; doctors cannot diagnose his illness, but thanks to a chance meeting this mystery will be solved; a woman undergoes a risky left temporal craniotomy.

A teenager is rushed to the hospital after taking aspirin to help alleviate altitude sickness; a woman has pain in her arm that mysteriously spreads.

A woman and her husband decide to start a family after numerous negative pregnancy tests; a man appears to suffer an embolism

A 3-month-old boy has breathing difficulties; a woman has stomach problems; stepping on a crochet hook causes strange problems for a patient.

An infant shows diverse symptoms; an ER nurse gets a diagnosis of lymphoma, before another symptom reveals her true illness.

Brenda and Jake are delighted when their daughter Isabel is born, but their euphoria quickly turns to panic when Isabel stops eating and her skin turns grey. Noah and Alexis were healthy twins until they suddenly lost all their milestones. Charlie, an active pastor, has difficulty reading; doctors must act quickly to save his eyesight.