Julie de Hauranne, a young French actress, arrives in Lisbon where she is acting in a film based on Letters of a Portuguese Nun by Gabriel-Joseph de la Vergne. Although she has never been to the city before, she speaks Portuguese, as it is her mother's native language. She quickly becomes fascinated by a nun who comes to pray nightly in the chapel of Nossa Senhora do Monte on the Graça hill. During the course of her stay, the young woman has a whole series of encounters, which, like her past existence, seem ephemeral and lead nowhere. But after a night when she at last speaks with the nun, she glimpses the meaning of her life and destiny.