In early eighteenth-century Venice an orphan girl discovers life and independence in the music of Vivaldi. The female musicians of the Instituto della Pieta play from a gallery in the church, their faces half hidden by metal grilles. They live segregated from the world. Cecilia, is a violinist who, during anguished, sleepless nights, writes letters to the mother she never knew, haunted by her and hating her by turns. She eats little and cannot sleep. But things begin to change when a new violin teacher arrives at the institute. The astonishing music of Vivaldi, the 'Red Priest', electrifies her and changes her attitude to life, compelling her to make a courageous choice.