After a piano concerto is performed at Carnegie Hall, scruffy vagrant Paul Marvan, an Austrian, walks onto the stage of the empty hall and begins playing a haunting piano piece with one hand. As Paul plays, he recalls how drastically his life has changed: A year earlier Paul is playing at the Salzburg Music Festival with a full orchestra. Afterward, Paul is introduced to wealthy American socialite Diana Fowler, who offers to sponsor Paul in America. As he is unemployed, Paul accepts, but finds life unsettling in New York City especially after he moves in with Diana and her adult children, June and Walter, who wonder if their mother is growing emotionally attached to the pianist. Later, Paul expresses concern to his agent, Mr. Shiner, over the inconsequential cities on his tour, but Diana reassures him. The tour begins and one night in Philadelphia, Paul goes into a bar for a late-night dinner and orders at length while the floor show act, dancers Margo and Carlo, twirl through a tango. Afterward backstage, Margo complains bitterly to Carlo about Paul's insensitivity of talking during their act. Upon discovering Paul's identity, Margo attends his concert the next night with the intention of disrupting his performance, but instead is enthralled by his playing. Margo meets Paul afterward and over dinner reveals she may be in New York soon auditioning for a musical show. Paul finds Margo attractive, but leaves the next day for the remainder of his tour. Back in New York, Paul settles into his own apartment, repaying Diana when he gets occasional concert dates. Some time later, Margo unexpectedly telephones Paul saying that she is in town and her show has flopped. She comes to Paul's apartment and explains that she has had an unpleasant break with Carlo and, fearful of his temper, has no place to go. When she pleads to stay with Paul, he grows alarmed at the implications, but she assures him it will only be for a short time. A few days later Margo learns her fears about Carlo were unfounded and prepares to depart, which upsets Paul. He implores her to stay while he goes on a brief tour, but she asks to accompany him instead. Strongly attracted to Margo and wary of convention, Paul takes her along and soon after marries her. Shiner breaks the news to Diana, who is disappointed. Poor weather brings a halt to the brief tour and, penniless, Paul requests an advance but discovers he has already taken out the maximum allowed. When Paul asks Diana for money, she refuses. Margo begins modeling to help pay the bills, but Paul quickly becomes jealous of her associations with men. Unable to secure any long-term bookings, Paul falls further into debt and when Margo loses her job, the couple moves into a small, tawdry flat. Paul agrees to play on a mixed program, which Margo scorns, but she responds enthusiastically when Carlo seeks her out for his new show. When Paul refuses to allow her to return to work, Margo secretly sees Carlo. Suspicious, Paul discovers her with Carlo and goes on a drinking binge, missing his concert, after which Shiner is unable to get him work. Margo turns down Carlo's offer and cannot understand Paul's willingness to play piano nightly in a bar. One night Paul phones Diana from the bar, again requesting money. Although deeply upset over his predicament, Diana refuses. Paul and Margo quarrel more and more about money and, when Margo suggests that he return to Diana, Paul tries to sell his music composition. Elated when a publisher appears interested, Paul telephones Margo only to learn that she is packing, having decided to leave him. Distracted, Paul is unable to play his piece at the publishing house and loses the deal. As he leaves the office, he stops by the printing presses and after avoiding a worker, sticks his hand into the machinery. Margo stays with Paul during his recovery and rejects Diana's offer of financial assistance, even after learning that Paul will never play again. Margo then hears that Carlo's show is a success and that he still wants her. While Paul files for the huge insurance claim on his hand, Diana visits Margo, who admits her marriage was a mistake. She asks Diana if she is in love with Paul, but Diana says she only cares about his ability to make music. Margo decides to return to Carlo and her career. When Paul arrives home from the hospital, he finds a farewell note from Margo and is informed by the insurance company that the worker who saw Paul at the publishing house has testified that the accident was self-inflicted. In the present, a crowd of derelicts have gathered in the empty hall and applauds Paul's playing enthusiastically. As Diana and June watch smiling, Paul happily plays for his new audience.
