The attractive Sandra Durani, studying to be a singer at the conservatory of music in the Italian town of Lucca, has a promising career in opera ahead of her; until that time, however, she's content to give public performances in her native town. On the eve of her nineteenth birthday, during a thunderstorm, the young singer leaves the apartment she shares with her mother Nicole Venturi, a correspondent for a major Roman newspaper. Sandra is on her way to a secret rendezvous with a married man: Marco Pierboni, a good-looking industrialist. The latter is killed by gunfire, however, shortly before Sandra arrives at the deserted villa outside the town which they had chosen as their meeting-point. Nicole has no inkling of her daughter's affair. She thinks that Sandra has gone to stay the night with a girlfriend. When Marco's corpse is discovered the next morning, ambitious journalist Nicole senses that reporting this sensational murder case will make her famous outside her local region. ...