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.