Based on

Movies like Donaumelodien (1936)

Stefan is the son of the owner of a Bavarian steamship concern, which plies the Danube. During a trip to Budapest, he falls in love with the beautiful Etelka, who, unbeknownst to Stefan, is the daughter of his father's Hungarian competitor. By chance, they lose sight of each other; but as Stefan's father enters into negotiations with Etelka's father about a merger of the two companies, the children find each other once again.