Waltz War

Joseph Lanner leads a Vienna-based waltz ensemble, while his first violinist Johann Strauss chafes under his leadership and begins composing his own waltzes. Lanner suspects Strauss is plagiarizing his ideas, fueling open tension between them. Lanner's daughter Katti is in love with timpanist Gustl, but Lanner disapproves of the romance.

Two emissaries from the British royal court arrive in Vienna to study the new waltz and bring it to London; Ilonka is a former lover of Strauss. Lanner has Strauss write down a new waltz on Strauss's monogrammed handkerchief as inspiration. Lanner conducts a performance, insults Strauss, and storms off, causing several orchestra members to defect and a brawl between the rival ensembles.

The British delegate is impressed by Strauss's playing and secures him a chance to go to London to present the waltz. The decision marks a turning point as the rivalry expands beyond Vienna.

In London, Queen Victoria longs to marry Prince Albert, inviting him to a waltz ball in hopes of swaying him. Katti, furious at Strauss's triumph, sails to London with her own women's orchestra to salvage her father's reputation. Ilonka returns to Strauss secretly to aid his London plan, while Gustl masquerades as Strauss to tutor Victoria.

Gustl, posing as Strauss, teaches Victoria the waltz, albeit with humorous missteps. Meanwhile Katti's orchestra performs from outside the window, and Victoria is impressed, while Strauss refuses to share the stage with a women's ensemble.

Just before the planned performance, Katti's band abducts Strauss by posing as rabid fans, whisking him away. Gustl, still masquerading as Strauss, conducts with surprising competence, guiding the crowd through Victoria's new waltz. In the crescendo of the moment, Gustl wipes his brow and discovers Lanner's composition written on Strauss's handkerchief.

The royal court warmly receives the improvised waltz, but Katti resents Gustl for seemingly betraying her father's work and ends their partnership. Victoria remains charmed by the music and the spectacle, while Strauss quietly contemplates his next move.

Towards the end of the performance, Strauss reappears and, hearing Gustl playing the Lanner-inspired waltz, decides to consider taking credit for the composition. The decision sets the stage for a formal showdown back in Vienna.

Lanner sues Strauss for copyright infringement, but the judges are divided on whether the waltz's style proves Lanner's or Strauss's authorship. The case moves toward a dramatic courtroom confrontation that could redefine their careers.

Katti and Susi trick Strauss into admitting the composition is Lanner's in front of witnesses, but Gustl counters by pointing out that he carried out the unauthorized performance, making him the one most at risk. The courtroom atmosphere tightens as loyalties clash.

In court, Strauss finally admits the composition is Lanner's and takes full blame to shield Gustl. The crowd splits into factions loyal to Lanner or Strauss, and the prospect of punishment hangs over the hall as tensions rise.

To placate the crowd, Strauss and Lanner begin composing a new waltz together, burying their differences and signaling a hopeful partnership. Katti and Gustl mend their relationship as the music mends the old wounds between the two men.