At a summer-evening dance a young girl meets a man who tells her he is a doctor. They go off together, and after that she never sees him again. She learns that she is pregnant and inquires about him at various hospitals, with no success. She reads of his engagement and becomes acquainted with another girl with a situation like her own.

The sisters Britta and Ellinor live with their grandfather, music professor Libergius, teacher and leader of the city's orchestra association. In the city there is also a youthful jazz band - to the professor's horror.

Unknown parachute troops land near Norrköping and the local home defense is alerted.