1905. A couple of cheerful traveling salesmen, Hansen and Larsen, are on their last round of visits to customers before settling down in the big city to open their own business selling women's underwear. They hold a farewell dinner for one of their old customers in Lilleby. There is a ball at the hotel, and a couple of young ladies make the acquaintance of the two friends, which will have consequences in more ways than one.

A woman is found strangled in her shop. Shortly after, another murder is committed. Perhaps the most terrifying is that the both girls' name is Sonja. The police is convinced it's the same killer and at each scene is heard a woman singing the same song. A song which is soon dubbed the 'murder melody.'

Christensen is the caretaker of a property in the inner city. He is a bachelor and has taken in a poor little girl. The house is inhabited by ordinary people, and the friendly caretaker is like a father to them. Up in the attic lives a whole colony of young artists: actors, dancers, writers and composers. They are poor, but they hold the flag high. They are confident that one day they will have their big breakthrough, and they are working diligently on a revue that their leader, a young musician and composer, has written.