The most likely theme in The Five-Forty-Eight is that of the male chauvinism that took place between the stereotypical "bosses and secretaries." The main character Blake has evidently seduced Miss Dent, and then abandoned her when the personnel department of his company dismissed her. Although she follows him as he heads home, and she appears to be "crazy" through the mentioning of her being a "mental patient," Blake remains confident. He goes to a gentleman's bar and ends up taking a later train home than normal.
Then when she appears on the train with a pistol, we see Miss Dent differently. She could easily shoot him when she takes him out to the freight house and coal yard, yet she is in control mentally after all. She shows him that she can forget him, and that she knows more about love and life than he ever will. He must grovel in the dirt--face down--as she delivers her last line of "Now I can wash my hands of you." The chauvinism has been addressed and although he will continue on, she has been able to move on without him. It shows her strength as a woman in a period when women had no rights to strength.