Old Virtanen is a respected night watchman at a textile factory and a single father to his daughter Aino, who is about to graduate from high school. The heartless factory owner Kuusela fires Virtanen, who is forced to look for a new job. When Aino, who is in love with the manager's son Veikko, disappears after her graduation party, her father, who has fallen ill with worry, is overcome with despair.