A woman, Gabrielle Darley, shoots a man, Howard Blaine, in the back as he is buying a wedding ring, then asks pardon and expresses love to his corpse as she waits for arrest. In her jail cell, she is supported by a kind matron. At her trial, she is asked to explain how she came to shoot Blaine, and she narrates her story. Blaine courted her and claimed he would marry her, and she left her unloving family to go with him to New Orleans. There, Blaine did not marry her but only took her to a house in a sleazy neighbourhood; in a bedroom there, a mirror vision of herself in bridal attire gave way to a vision of herself in a red dress (strikingly hand-coloured in the film), indicating that she knew she was entering on a life of prostitution. She gave in for love of Blaine, and spent several miserable years servicing men he sent in to her, spurred on by little love notes from him.
The mocking prosecutor suggests that she shot Blaine out of jealousy because he was going to marry another woman, and she acknowledges this and points out that he was buying the ring with money she earned for him. Women in the courtroom cry. Despite the prosecutor’s finger-wagging and the judge’s frivolous boredom, the all-male jury deems her not guilty.
Gabrielle tells the kind matron that she would now like to redeem herself by working to help people, and drops her brilliant red dress on the floor as a sign that she will never go back to that work. Beverly Fontaine, a society matron fond of getting publicity by taking up reformed criminals, invites her to come live at her house. There, she meets the nice chauffeur Terrance O’Day, but is put on display at parties for Beverly’s friends and tormented by tactless questions about her prostitution work. Terrance takes her on a sweet, wholesome date to an amusement park, and she realizes that there is a good kind of man she has never encountered before.
Beverly gets tired of her and goes on a trip, with Terrance driving her, leaving Gabrielle a letter to the superintendent of a local hospital about training as a nurse. The superintendent, however, recognizes her and throws her out. She is unable to get work, losing her job as a maid when she gets upset at seeing her defense attorney’s wife wearing her ring she had to give him as her fee. Starving and desperate, she telegraphs to Clara, a supportive friend in the New Orleans brothel, to send her the train fare to return there and take up her old profession. Clara does.
The telegraph operator is a friend of Terrance’s, and goes to Beverly Fontaine’s house to tell him of this just as she and Terrance return from her trip. Terrance throws up his job and commandeers Beverly’s car to drive to the train station to stop Gabrielle, but is five minutes too late. He gets on the next train, and, in New Orleans, takes a taxi to the address on the telegram. Meanwhile, Gabrielle, hesitating on the doorstep of the brothel, is attacked by a brute, and is hit by a car as she runs from him. Terrance sees the accident, but does not realize it is she. Hearing from Clara that she has not shown up yet, he hangs around the street looking for her for days.
Gabrielle is recovering in the hospital when she overhears staff people saying that, because the U.S. has just entered World War I and the flu pandemic has started, they are in desperate need of additional nurses and helpers. She offers herself, and is hired. She is scrubbing the hospital floor when Terrance enters in uniform, having enlisted and serving as an ambulance driver. They are reunited, and he asks her to marry him before he goes overseas. She declares her love but postpones their marriage till he comes back and she has worked longer and become worthy of a happy life with him.
A woman who has been keeping an album of clippings about Gabrielle, who seems to be Beverly’s maid, tells us that this happy life was attained for these two. But Gabrielle is only one of many women in this terrible situation, she says, and it is up to all women to help their unfortunate sisters.