Blood is removed from a horse that has been given diphtheria toxin. This antitoxin blood is purified to make antitoxin. This process is shown in an animation. The antitoxin in bottled for use by physicians. Next, the processes in modern diphtheria control are demonstrated. In a dramatisation, a doctor examines a young girl who is sick in bed. He diagnoses diphtheria and cultures are taken for examination by the city health department. The next morning the cultures are examined.