No one would inflict external injury to himself—because the consequence is immediately seen and felt. The lungs, however, being out of sight, can be subjected to years of abuse before a smoker takes warning. In this film, Dr. D.W. Thompson of the Toronto General Hospital demonstrates, through a series of color slides of lungs and lung tissue, how the persistent, prolonged irritation of cigarette smoke can bring about drastic, even fatal, changes in the lungs—convincing evidence that smoking can and does cause cancer and other lung disease. A film for the lay audience as well as for use by medical personnel.