In a shadowy antiques shop in Rome, violinist Julia Ansdell happens upon a curious piece of music --- the Incendio waltz --- and is immediately entranced by its unusual composition. Back home in Boston, from the moment Julia’s bow moves across the strings, drawing the waltz’s fiery notes into the air, something strange is stirred. The music has a terrifying and inexplicable effect on her young daughter, who seems violently transformed. Convinced that the hypnotic strains of Incendio are weaving a malevolent spell, Julia sets out to discover the man and the meaning behind the score.