A famous industrialist is murdered at a restaurant in Malmoe. Police inspector Martin Beck in Stockholm gets the case. The suspects lead to people involved in illegal arms deals. But who was the biggest criminal, the murderer or the industrialist?

Emma Klink is devoted to preserve morality in 1912 and she is also a chairwoman for "The support for unmarried mothers". Her husband is a mustard manufacturer who has had a secret affair with a Spanish dancer twenty-five years earlier. His mistake is that he confides in a semi-senile vicar, and when a strange young man suddenly appears shouting "Daddy!" chaos enters the once peaceful house.