Stefan Knüpfer, Steinway & Sons' captivating concert technician and piano tuner, assists an assortment of famous concert pianists in the quest for the perfect sound. Armed with humor, patience, and a generous dose of creativity, he fiddles with the grand pianos as long as it takes for their sound to seduce the pianists. This is not always an easy task -- "Pianists are never really satisfied," Knüpfer confides to the camera. If necessary, he tinkers with the hammer heads until deep into the night, or goes to work like a true inventor with electric drills, tennis balls, and "sound reflectors" that he concocted himself. In the build-up to Pierre-Laurent Aimard's Bach recordings in the Wiener Konzerthaus, the tension can be cut with a knife. Will Knüpfer manage to find an alternative for Aimard's favorite Steinway, which much to his horror has been sold? He begins a quest for a new grand piano that will meet the expectations of this perfectionist pianist. In between all the stress, the concert halls that Knüpfer visits elicit a great deal of beautiful music, performed by pianists like Lang Lang, Alfred Brendel, and Rudolf Buchbinder.