Based on the play Signora Cacilini by Edward Sheldon, a young clergyman falls in love with a beautiful opera singer with a past.
Harry tells his grandfather Bishop Tom Armstrong that he wants to marry an actress, and the Bishop tells him the story of his romance fifty years ago.
Cornelius Van Tuyl (Lewis Stone) and Rita Cavallini (Greta Garbo) recall their past romance as Rita says that love is a beast of the night that dies in the morning. Young Tom Armstrong (Gavin Gordon) meets Rita and as a rector preaches to her after she mocked Madame Cavallini's looks. He wants to see her again, and she gives him a flower before he learns she is the notorious Cavallini. Cornelius asks Rita if she will marry Tom. In six weeks he has not said he loved her, and she will not marry him even though she loves him. Cornelius tells her to end it, and she agrees; but she quickly changes her mind. Cornelius reminds her that Tom's happiness or heartbreak depends on her.
Tom calls Rita a dream and asks her not to leave town. She says that only today is real. Tom gives her a locket with his baby photo and sings to her. He cancels his meeting with the vestrymen. He speaks of love as working together, but to Rita love is only a moment in someone's arms. Tom asks Rita to marry him, but she says she cannot because their lives are different. Yet she says he is the first man she really loved. She tells of the first man who sold her after a few hours and mentions Cornelius. Tom makes her swear that there was nothing wrong between her and Cornelius. Cornelius comes in, and Tom tells him of their engagement. Rita then tells Tom of her relationship with Cornelius. She thanks Tom for having loved her and leaves.
Rita does not want to sing the opera, but Cornelius persuades her. After her farewell parade Cornelius tries to console her at a private dinner. Rita feels she lost a dream of love. As Tom is arriving, Cornelius asks her forgiveness and thanks her before leaving. Tom tells Rita how he saw her everywhere; he wants to save her, and she says she learned from him. They kneel to pray, but instead he says he wants her as a woman. She tells him to go away and not treat her as other men did but to let her keep her soul. Tom bows to her and says good-bye. Fifty years later Bishop Armstrong tells Harry how he later married and that he just learned that Rita died at a convent. He tells Harry not to lose romance, the greatest thing in the world.
This bittersweet romance shows the difficulty when differing lifestyles make a marriage for two lovers impractical. The gulf between the naive minister and the amorous opera star is too large to be bridged. Tom's advice to his grandson implies he regretted rejecting Rita because of her past.