The small and remote Austrian town of Arnstein has built a new landing stage for the Danube steamers to call. First passenger is Helga, a young architecture student who has left her study course. She returns to her foster-mother Therese and is welcomed, but Therese relies on her inn for a living and it's mortgaged to the hilt to Kilian, who threatens to foreclose. Helga uses her feminine charm to get some breathing space. Inevitably Helga quickly finds romantic involvement in the small town, with Fred, and together they borrow furniture and fittings without permission from the unoccupied local castle to liven up the inn. This becomes a major attraction with young people, (cue rock'n'roll music and dancing) and everything looks to be running well until the castle's owner suddenly returns. For a moment things look black ... with Therese still in debt, what will become of them all?