The film stars Rosalind Russell, Alexander Knox, and Philip Merivale.

The film was adapted by Alexander Knox, Mary McCarthy, Milton Gunzburg (uncredited), and Dudley Nichols from the book And They Shall Walk, by Elizabeth Kenny and Martha Ostenso, and directed by Dudley Nichols.

In 1911, Elizabeth Kenny returns from nursing school in Brisbane, Australia, to her home in the bush of Queensland.

Three years later, Elizabeth visits a ranch to treat a young girl, Dorrie, who is contorted in agony.

His reply: infantile paralysis, no known treatment, "do the best you can with the symptoms...” Elizabeth treats “spasming” muscles with heat, wrapping Dorrie in steaming flannel.

After her muscles are “re-educated”, Dorrie makes a complete recovery, as do five other cases of polio that Elizabeth treats.

She assumes that she has done the usual thing in treating polio and is horrified to learn that infantile paralysis is a deadly, crippling disease and that the standard treatment is agonizing immobilization.

Brack scoffs at her theory and refuses to consider the possibility that the science of the past 50 years may be wrong.

At that time, Australian nurses had to be single; she is about to marry Captain Kevin Connors.

Kevin leaves to fight in World War I. Elizabeth joins the Army and finds him in a hospital at the front.

A reporter reads her a press release from the University of Minnesota, stating that the Kenny method will form the basis of all future treatment.

After three years' work in Minneapolis, Sister Kenny dictates a letter to Dr. McDonnell.

At the end, a crowd of children gather outside the Institute, singing “Happy Birthday” to Sister Kenny.