In the mid-1960s, three small-time Finnish bootleggers seize control of their Helsinki neighborhood's black-market liquor business.
Nina, Erik, and Heikki are charged in court and receive prison sentences, with the girl receiving a suspended sentence. Erik's father Tauno returns home and finds Nina waiting for him. The girl recounts the events that led to the situation, which are presented in flashback.
Mirja finds her grandmother's old hat in the attic and sets off singing along the road with it on her head. On her journey, she meets composer couple Theodor and Thea Tekonen and gets a ride from hat maker Kosonen and his son Ilmari, who falls in love with Mirja. However, the girl continues her journey alone and, with the help of the circus troupe leader, gets to perform at Linnanmäki, where Ilmari finds her again.
