In a dimly lit antiques shop in Rome, the violinist Julia Ansdelл stumbles upon a yellowed sheet with a musical notation—a waltz by a composer she has never heard of. Julia is delighted by this music, full of suffering and passion. Returning home to Boston, she begins to learn the waltz, but suddenly discovers that this melody has an inexplicable, frightening effect on Julia’s small daughter. Convinced that the hypnotic sounds of the waltz cast some kind of evil spell, Julia decides to dig up the whole truth about the person who created the music that threatens the very existence of her family…