Plain-looking seamstress Dorothy Atwater lives in a boardinghouse bustling with noisy neighbors, including Prof. Hector Martin, who teaches music lessons next door. One day, Hector hears Dorothy sing a high note and pulls the delighted girl into his room to repeat it, only to reveal that he is using her to demonstrate poor pitch. When Hector realizes that he has insulted Dorothy, he apologizes and they strike up a friendship. Soon after, as Dorothy babysits for a neighbor, Hector’s student Eddie Flynn croons a new love song that entrances all the women on the hall, including Dorothy. That night, a neighbor couple’s loud argument attracts the attention of Dorothy and Hector, who decide to call the police. While they wait, Hector admits his dream to own a baby grand piano on which he will finish his opus, “Fata Morgana,” or “Mirage.” Hector urges the shy, practical Dorothy to reveal her dreams, and finally she confesses her desire to have men admirers whistle at and send flowers to her. Dorothy notes that she prays for her dream to come true, while Hector, a Jew, says he prays only for larger requests, like peace and inspiration. One day, Hector leaves to attend a Passover service at the synagogue at the same time that Dorothy leaves for an Easter service. Inspired, Hector proposes that they each visit the other’s places of worship, declaring that their Gods “should work together.” At each service, they pray for each other, and days later, Dorothy is thrilled to be whistled at by boys on the street. She runs to inform Hector, who insists that God listened to his prayers. Eddie then shows up for a lesson, at which Dorothy harmonizes with him beautifully on a song. The lesson is interrupted when the boys from the street knock at the door, but Hector pushes them into the hallway, where, out of Dorothy's hearing, they demand their pre-arranged payment from him for whistling at Dorothy. Later, Hector convinces Eddie, who has a girl friend, to send Dorothy flowers to brighten her day, and Dorothy is transfixed by the bouquet. She then visits her new client, wealthy Irene Hoffman, a widow who finds the quiet of her Beverly Hills home stifling. When Irene visits Dorothy at the boardinghouse, she is thrilled by the lively, boisterous atmosphere, and promptly commissions a new wardrobe. Listening to the apartment house’s “symphony of humanity,” Irene is lulled to sleep, and by the time she awakens, is charmed to find the neighbor baby and a little dog sleeping next to her on Dorothy’s bed. The next day, Eddie helps Dorothy carry in her groceries, but when she presents him with a gift, he feels guilty and reveals that he bought the flowers only to please Hector. Dorothy hides her disappointment, but alone in her room later, bursts into tears. When, soon after, the boys on the street cease whistling at her, she reveals to Hector that she knows what he has done, and he once again apologizes. At Irene’s the next day, Dorothy spots a baby grand piano sitting unused in the study, and, hoping to convince Hector that her prayers worked, too, asks Irene to donate it to him anonymously. Irene is reluctant because the piano is all she has left of her musician husband, until late at night she hears music mysteriously drifting from the piano and realizes that her beloved wants the instrument to be used. The next day, while Hector is out, they hire moving men to transport the piano through the window into his room. Hector returns early and Eddie conspires with Dorothy to keep Hector out of his room. When Hector insists on going home, however, he opens the door to find the piano floating through the window. Dorothy, Eddie and Irene rush in to explain, and Hector, moved beyond words, plays the lovely “Fata Morgana” for them. That night, Eddie visits Dorothy, depressed because he has lost his audition and quarreled with his girl. Dorothy urges him to take her to a movie, at which they hold hands, and later asks for a kiss goodnight. Surprised at what a nice night he has had, Eddie agrees to kiss Irene “like a brother,” but inexplicably finds himself holding her in his arms. He goes home but immediately calls her, and they fall asleep with their phones cradled next to their ears. In the morning, Eddie wakes Dorothy by saying hello over the phone, after which he teases her for “spending the night” with him. Dorothy relates these events to Irene, who counsels her to let down her hair and replace her glasses with contact lenses, and then arranges for a full beauty makeover for Dorothy. Pleased with a job well done, Irene then invites Hector to dinner, at which Hector admits that he is lonely and asks for her help in finding him a woman. Hector, tipsy, thinks he sees angels in the shadows on the porch, only to realize that it is Eddie and a newly gorgeous Dorothy, very much in love. Dorothy states that they should include each other in all their prayers, since God is very busy and needs people to help him perform miracles. Hector laments that his prayers have not all been answered, but Irene points out that the answer to his dream is sitting right next to him. At the lavish double wedding of Dorothy to Eddie and Hector to Irene, Hector and Dorothy agree that next, they will pray for babies.