Eighteen years after her daughter Mary disappeared, Evelyn Dow contracts pneumonia. In her delerium, she calls for Mary, and the doctor, not knowing the story, recommends that her husband Henry bring their daughter to her bedside to ease her anguish. Believing his wife to be dying, Henry asks a friendly young waitress, Sally Gates, to impersonate Mary. Her appearance eases Evelyn's mind so much that she recovers against all odds and Henry begs Sally to continue the masquerade. Sally is happy for a time but, unwilling to continue lying to a woman she has come to love, and missing her old friends, she runs off one night to the dance hall where she used to go after work. She wins a contest with her former boyfriend Jimmie Kane, but soon realizes that she does not fit in here anymore either. A dog, belonging to wealthy young Peter Marshall, follows her home when she leaves the dance. She meets Peter when she reluctantly returns his dog to him and is attracted to him against her will. A few days later, Evelyn and Sally plan a trip to Europe to complete Evelyn's convalescence. While they are gone, Henry formally announces that his daughter has been found. After Peter sees the news in the papers, he visits Sally in Europe and they fall in love. Sally is afraid to tell Peter the truth about her background. One night, they take a cab driven by Jimmie, who uses his information about Sally's real identity to extort money from Peter during a party at the Dow residence. Martin, a waiter at the party, overhears their negotiations and takes over the blackmail scheme. Sally, meanwhile, leaves the party and returns to her old neighborhood, determined to fool Jimmie into believing that she is not the same woman who is living with Henry and Evelyn. Martin sees her there, and thinking that she is Mary's double, suggests that she pretend to be the real Mary. Sally learns from Martin that he knows she cannot be the real Mary because he was the person responsible for young Mary's kidnapping and murder. The police capture Martin, and Peter, who loves Sally for herself, announces his engagement to her. Later, Henry starts to tell Evelyn the truth about the woman she thinks is her daughter, but she stops him, preferring to enjoy what she has.