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'.
Gull-Maj Norin
as Odette Margot / Sonja
Poul Reichhardt
as Max Stenberg
Angelo Bruun
as Louis Valdini
Else Petersen
as Mrs. Baunsø
Ib Schønberg
as Theatre director Perm
Peter Nielsen
as Assistant Detective Baunsø
Karen Poulsen
as Flora Kristiansen
Petrine Sonne
as Sonja Bohman
Charles Wilken
as Boarding House Host
Per Buckhøj
as Markussen
John Pio
as
Anna Henriques-Nielsen
as Sonja Neie
