This autumn, Dr. Earl Headley is eagerly demonstrating what seems to be a miraculous cure for tuberculosis. Yet not far from where he is working, the disease seems ready to claim yet another life, a young woman named Winifred, who is already seriously ill. Winifred's mother and younger sister Trixie are devastated by the news. When Trixie hears the family doctor say of Winifred that "when the last leaf falls, she will have passed away", she interprets the doctor's words literally. Thinking over what she has heard, she determines to do everything possible to save her sister.