When a 19th century nun elopes, the Virgin Mary takes her place at the convent.

In 1812, in the village of Miraflores, Spain, the orphaned Teresa, a musically talented postulant at the convent of Miraflores, is struggling to be a good nun, but is also attracted to worldly ideas of romance and "knights in shining armor." She serves penance for her frequent disobedience, which causes an older nun, Sister Domenica, to call her a gypsy. Despite her lapses, she is happy at the convent and her love for the Mother Superior is surpassed only by the devotion she feels for the statue of the Blessed Virgin that holds a place of honor in the chapel. She prays often, projecting onto it her feelings for the mother she never knew. The villagers, too, take pride in the statue and believe that St. Mary reciprocates by blessing their fields with abundant crops and good weather. During a church festival, as the villagers and a band of pickpocketing gypsies mingle, a regiment of British dragoons march through the village, in preparation for battle with Napoleon's army. Teresa catches the eye of a handsome captain, Michael Stuart, who rescues a young child from being trampled. Overcome with new feelings, Teresa prays fervently to the Virgin to bring victory to the captain and his men. Although the soldiers win the battle, they suffer many casualties and the convent is turned into a hospital for their wounded. Among the severely injured is Michael, who suffers from a bullet near his lungs. Again Teresa prays for Michael's life, promising to be a good nun in return. Michael, a nephew of the Duke of Wellington and a native of Devon, survives and takes a special interest in Teresa. During one of their conversations, Teresa sees the pocket watch Michael carries, which he explains has been in his family for generations. Although he asks her to marry him, Teresa refuses, feeling obligated to take vows in return for her answered prayers. However, when Michael leaves to join his troop, she chases after him and agrees to meet him at the inn. The pleasant weather turns into a storm when she returns to pray at the foot of the statue, begging for guidance. During a clap of thunder, Teresa removes her robe and runs away into the rain, and the Virgin steps down from her pedestal and puts on the robe. When the Reverend Mother later comes to the chapel, she finds the statue missing and a woman she assumes to be Teresa serenely praying at the altar. On her way to the inn, Teresa discovers that the French are burning the village and sees corpses of English soldiers strewn on the road. When a French sergeant attempts to rape Teresa, the gypsy matriarch La Roca and the gypsy troubadour Flaco, who are looting in the wake of the French, intervene and take her to their camp. Among the stolen items is Michael's pocket watch and when Teresa hears that the English soldier from whom it was taken is dead, she discards the cross at her neck and renounces her faith. Taking up life with the gypsies, she sings sad songs at their campfire. Anxiously, La Roca watches her sons, Carlitos and Guido, compete for the attention of Teresa, who is oblivious in her mourning. Meanwhile, Michael, who is alive, escapes from a French prison camp and flees to unite with Teresa at Miraflores, where the disappearance of the Blessed Virgin's statue is blamed for an unending drought. To the Reverend Mother, Michael explains how his orderly robbed him before fleeing and was subsequently killed by the French. In a processional of nuns, Michael spots the image of Teresa, radiant and changed, and Mother Superior tells him that she has taken her vows and become an exemplary nun. Sadly, he proceeds to meet his regiment in Portugal. Eventually, Teresa agrees to marry Guido, but, on the day of their wedding, the jealous Carlitos betrays his brother to the French, who want him for robbery. After Guido is ambushed and killed, La Roca blames Teresa for her sons' discord and Guido's death, and orders her to leave camp. Hoping to win her affection, Carlitos follows Teresa, but is shot down by La Roca, who had dreamed a premonition of his death the night before. After intercepting the fleeing Teresa, Flaco offers to accompany her to Madrid. In the city, while Teresa distracts the crowd, Flaco picks their pockets. She gains the attention and, soon, the patronage of the great matador, Cardoba, who sponsors her as a café singer. Although the gallant Cardoba never smiles, he ardently wishes for her love. She never gives in to her feelings, however, believing that her love brings bad luck to the recipient. Instead, she takes up with an older aristocrat, Casimir, who arranges for her to perform in concert halls, and she becomes famous as "Miraflores the Gypsy." Hurt by Teresa's rejection, Cardoba takes risks in the ring, causing rumors that he is "losing his luck." Although she will not proclaim her love for him, Teresa's concern prompts her to attend his bullfight. After dedicating the bull to her, Cardoba successfully completes a series of maneuvers which has the crowd cheering. As he acknowledges their acclaim and smiles at Teresa, he is charged by the bull from behind and killed. In grief, Teresa leaves Casimir, who believes he will die from her absence, and embarks on a performance tour of the major cities of Europe as "La Miraflas the Gypsy" accompanied by her friend Flaco. In Brussels, she is reunited with Michael after she spots him in a parade. Again, he asks for her hand, but she superstitiously refuses, fearing for his safety. At a ball during which she meets the Duke of Wellington, the soldiers are ordered to leave for battle. Before departing, Michael mentions that the statue is missing from Miraflores. Disturbed by a foreboding, she searches for a chapel in which to pray and begs that Michael be returned to his people and given a long life. Then, after making arrangements with a priest, she and Flaco set off for Spain. During a bloody battle, Michael miraculously escapes death. On his return to Brussels, the priest gives him a letter from Teresa, which begs him not to follow her. Although the priest does not believe Teresa's "superstition" that she bargained with the Blessed Virgin for Michael's life, he notes that the dents on Michael's helmet indicate how closely he came to dying. When Teresa and Flaco reach Miraflores, which has been decimated by a four-year-long drought, Teresa bids Flaco, her "true friend," goodbye. In the chapel she prostrates herself and prays, unaware that a shadow of a veiled figure reaches toward her and then mounts the pedestal. When Teresa looks up, she sees the statue standing in its rightful place. A storm then breaks out, drenching the fields and prompting the nuns to come in gratitude to the chapel. There, unaware that Teresa had ever left, they find her praying at the foot of the miraculously restored Blessed Virgin.

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