The infamous jewel thief "Will O'the Wisp," works with her partner Carl at a beer garden in Austria under the name of Steffi. They are nearly arrested while they are singing onstage at the beer garden after cleverly robbing a jewelry store during intermission, but escape with their partners Von, Rita and Bako. They split up in the woods after arranging to meet in a nearby town. Carl and Steffi follow the sound of classical piano music to a remote cottage. There they meet elderly Langauer, a famous concert pianist who retired from playing when he began to lose his memory and faltered during performances. Steffi is a great admirer of Langauer, and with her help, he is able to play complete concertos on the piano. Unaware that Steffi and Carl are fugitives, Langauer, who is normally a hermit, graciously accepts them into his home as guests, with the assistance of his maid Lieschen. After the police come and Carl and Steffi successfully avoid recognition, they leave Langauer's home and meet up with their partners, whereupon they decide to return to Langauer, because their way across the border is barred by electrified fences. Von poses as a manager and promises Langauer to help him back onto the concert circuit, but when the news is leaked to the press, the imposters are inundated with reporters and friends of Langauer. One friend, Polesie, becomes suspicious of Von and investigates. Steffi is hearbroken, however, because she realizes that her cohorts have no intention of going through with the concert plans, and that Langauer will be hurt. The local burgomaster organizes a festival in Langauer's honor, and there the pianist gives his premiere performance. Von, Bako and Rita escape during the rush of the crowd and the festivities, but Steffi stays behind, insisting that she help Langauer through the performance. Carl also stays behind, and when Steffi is arrested and Langauer falters, Carl accompanies him on the violin to lead him back to the music score. Carl then gives himself up, and the town officials hint they may go easier on Carl and Steffi because of their self-sacrifice. His confidence restored, Langauer successfully completes his concert.