Emergency!

A woman returning from Asia with a monkey also brought back a highly contagious virus that kills a firefighter and sickens Dr. Brackett, later Johnny too is stricken during a rescue of a man having a heart attack on a scaffold, of whom the rescue fails. But the woman is not as sickened and her traveling partner appears to have immunity to the disease. As two professionals are fighting, Dixie talks to the wife, whose husband is (of course) dying. While Dixie, Dr. Early, and Roy treat Johnny, Nurse Walters and Dr. Early treat Dr. Brackett; his conjecture about the woman's immunity (which he makes before he himself is sickened) proves to be crucial to finding the treatment for the virus. The firefighters also rescue a boy with Ménière's syndrome, from a treehouse.