In Milan, an unwed mother, forced to flee from her town because of the scandal, meets a doctor who falls in love with her and marries her. But the couple's relationship breaks down almost immediately: the husband is unable to leave behind the woman's past and can not stand a son not his. So Dina, in an attempt to readjust the rapport, entrusts the child to the care of the mother of her seducer (meanwhile deceased). But the sacrifice is beyond her strength, and she's soon taken by the irresistible desire to get her child back: in damp and foggy night, on her way to the station...