During a transvestite ball, a young provincial meets Fanny Legrand. A great love is born between them. Later, the young man learns that Fanny was a great coquette. He leaves her, he comes back, he forgives. But when he embarks for America, Fanny does not follow him.
A man who suffers from the delirium of persecution and to the point of trying to strangle his wife is interned. His brother, needing his signature for his own business, gets him out of the asylum with the complicity of a false magistrate and against the advice of the doctor.
The story begins at a concert during which Beethoven's Concerto in D major for violin and orchestra is performed. Romaine, a mysterious woman, is in the concert hall. Pierre, her husband, is first violin of the Orchester Colonne. That evening, she discovers Marcel, a brilliant concerto soloist, and falls in love with him. Pierre and Marcel are friends, which complicates the situation. Pierre invites his friend to the house, without suspecting what will happen. The young woman, trying to find a clever pretext for a one-on-one meeting, quickly reveals her feelings to Marcel.
A famous academic, very in love with his much younger wife, has every reason to believe that his love is reciprocated. He learns that he is being cheated on and falls seriously ill. His wife cares for him tirelessly and he understands that she has always given him the best of herself.