Julie de Hauranne, a young French actress whose mother is Portuguese, visits Lisbon for the first time. She is there to act in a film inspired by Guilleragues' "Letters of a Portuguese Nun," an infamous 17th-century work, widely believed to be a work of epistolary fiction.
Julie becomes fascinated by a nun who prays each night at the Nossa Senhora do Monte Chapel on Graça Hill. During her stay, the young woman has a number of encounters that, at first, seem ephemeral and without consequence. But one night, after finally speaking with the nun, she glimpses her destiny and the meaning of her life.