Teresa, a postulant at the convent of Miraflores in Salamanca, Spain, is an orphan taken in by the sisters there. She thrives in the convent life, even though she can be a handful for her superiors. She fills her days with songs about worldly love for the other postulants and with readings of secular tales and plays such as Romeo and Juliet. Yet she also maintains a deeply sincere devotion to Christ and to His Blessed Mother. A statue of the Virgin Mary, in particular, is held in high esteem by Teresa as she goes about her duties—the Madonna, Maria Carmi.
When the British march through the town en route to confront Napoleon’s French forces, Teresa is drawn to a dashing captain she spots while he waters his horse. After the British victory at the Battle of Salamanca, the regiment returns to the convent, which the Mother Superior offers up as a hospital for wounded soldiers. Here Teresa learns more about the young captain who captivated her: Michael Stuart. He finds Teresa fascinating, and before long the two are drawn to one another and begin to fall in love.
Recovered in time, the soldiers move on, billeted in the nearby town of Miraflores. Teresa, now consumed by desire, considers leaving her religious calling for Michael. Michael asks Teresa to marry him; she hesitates but runs after him, and they kiss. He suggests they meet at the town inn if she truly wants to abandon the religious life to marry him.
In the chapel, Teresa begs for guidance. When no sign comes, she strips off her postulant’s habit, wraps a cloak about herself, and rushes out into the night to meet Michael. At that moment a miracle occurs: the cherished statue of the Virgin Mary comes to life, dons the discarded habit, and secretly takes Teresa’s place at the convent.
A thunderstorm roars as the Holy Mother steps from the pedestal, and it is the last rain the valley will see for several years. A drought grips the countryside, and the townspeople believe the Virgin Mary has intervened to bring abundance—an belief that appears to have truth, as crops suffer when the statue vanishes.
The French return and ravage the town. Teresa is nearly raped by a French sergeant, but is saved by a band of gypsies. Among them is a handsome young man who becomes central to Teresa’s life for a time. He holds Michael’s watch, a token Teresa recognizes when the case is opened and the tune it plays is heard again. Rumors and jealousy swirl within the gypsy camp, and Teresa—now embittered—begins to question Christianity, even discarding a crucifix necklace in a moment of anger.
Unbeknownst to Teresa, Michael has been captured and later escapes, returning to the convent in hopes of taking Teresa with him to England to marry. He discovers that Teresa has taken final vows and become a nun, while the woman he loves appears to be living in Teresa’s place. Distressed, he confronts the apparition in a processional march and learns that the Virgin Mary herself has been impersonating Teresa. Broken by what he believes to be a cruel twist of fate, Michael leaves to resume his duties.
Meanwhile, Teresa faces heartbreak and disillusion as she travels across Europe. She becomes a celebrated singer, drifting from Madrid to other cities, where she is pursued by wealth and fame. In Madrid she flirts with Cordoba, a bullfighter who is tragically gored in the arena, his death making Teresa feel as though she is somehow bad luck to those who show her kindness. She even abandons a commission portrait Casimir had commissioned from "my friend, Goya," leaving him in despair when he discovers her sudden departure.
Four years pass as Teresa tours Belgium, where a ball for British officers is planned—an event that provides a chance encounter with Michael. The two lovers meet again, and Teresa, now confused about herself, wonders why Michael did not come back for her after his escape. Michael explains that he did return to find her, but the sight of her in nun’s habit—whether real or imagined—haunts him. He asks Teresa to pray for him as the ball proceeds and as Wellington’s troops prepare for renewed action.
Teresa reaches a turning point as she prays for guidance in a church, seeking to reconcile her love with her vocation. She decides to return to the convent and leaves with Flaco, a loyal Gypsy ally, in a coach. The following day Michael leads a cavalry charge that breaks Napoleon’s lines. He is struck by a cannonball but survives, his helmet scarred by shrapnel, a sign that he has been spared—if only by a grace he cannot fully explain.
Michael returns to Teresa’s flat, and she sends for the priest to help guide them. She begs him to counsel Michael to accept her choice to return to her vocation and to honor her decision. In Salamanca, the drought that has plagued the land for four years persists until a moment of divine intervention. The statue of the Virgin Mary reappears on its pedestal as Teresa prays in the chapel, now properly habited and in prayer herself. A thunderstorm follows, the drought ends, and the people rejoice. The town gathers in the convent chapel as the nuns, joined by villagers including Flaco, bear witness to the miraculous return of the statue. The scene closes with the community singing Mozart’s Ave verum corpus in a gesture of gratitude and awe.
