Fourteen-year-old Bernadette Soubirous lives in relative poverty with her family in Lourdes. At her Catholic school, Bernadette is shamed by her teacher, Sister Vauzou, for falling behind in her studies because of her asthma.Later that afternoon, while she is fetching firewood with her sister Marie and school friend Jeanne outside town, Bernadette is left behind at the Massabielle grotto when her companions warn her not to wade through the cold river for fear of taking ill. About to cross it anyway, Bernadette is distracted by a strange breeze and a change in the light. Investigating the grotto, she sees a beautiful lady dressed in white, holding a pearl rosary. She tells her companions, who promise not to tell anyone else. However, Marie tells their mother when they return home, and the story soon spreads all over Lourdes.Many, including Bernadette's Aunt Bernarde, are convinced of her sincerity and stand up for her against her disbelieving parents, but Bernadette faces civil and church authorities alone, including Abbé Dominique Peyramale. Repeatedly questioned, she stands solidly behind her seemingly-unbelievable story and continues to return to the grotto, as the lady asked. She faces ridicule since the lady tells her to drink and wash at a spring that does not yet exist, but Bernadette digs a hole in the ground and uses the wet sand and mud. Water later begins to flow and exhibits miraculous healing properties. On Bernadette's last visit to the grotto, the lady finally identifies herself as "the Immaculate Conception." When civil authorities try to have Bernadette declared insane, Peyramale, who once doubted her, now becomes her staunchest ally and asks for a formal church investigation to verify if Bernadette is a fraud, insane, or genuine.The grotto is fenced off and the Bishop of Tarbes declares that unless the Emperor orders the grotto to be opened, there will be no investigation. When the Emperor's infant son drinks the water and is cured of his illness, the Empress believes his recovery to be miraculous and, at her insistence, the grotto is reopened. The Bishop of Tarbes then directs the commission to convene. The investigation takes many years, and Bernadette is questioned again and again, but the commission eventually determines that Bernadette truly experienced the visions and was visited by the Virgin Mary.Afterwards, Bernadette intends to live an ordinary life, but Peyramale does not think that it is appropriate to turn Bernadette loose in the world and persuades her to become a nun with the Sisters of Charity of Nevers. Bernadette undergoes rigorous spiritual training and works hard at the convent, but she is also subjected to emotional abuse from Sister Vauzou, now the mistress of novices at the convent. Vauzou reveals to Bernadette that she is skeptically jealous of the attention that Bernadette has been receiving as a result of the visions and says she is angry that God would choose Bernadette instead of her, when she has spent her life in suffering in his service. She asserts that Bernadette has not suffered enough and wants a "sign" to prove that Bernadette really was chosen by Heaven.Bernadette makes a revelation to Sister Vauzou that is later diagnosed as tuberculosis of the bone; the condition causes intense pain, yet Bernadette has never complained or so much as mentioned it. Vauzou, realizing her error and Bernadette's saintliness, prays for forgiveness and vows to serve Bernadette for the rest of her life. Despite the severity of her illness, Bernadette adamantly declines partaking of the grotto's healing waters. Knowing that she is dying, Bernadette sends for Abbé Peyramale and confesses to him her feelings of unworthiness while she sorrowfully maintains that she will never see the lady again. However, the lady appears in the room, smiles, and gestures to Bernadette warmly. Bernadette joyfully cries out to the apparition before finally dying. Upon her death, Peyramale remarks, "You are now in Heaven and on earth. Your life begins, O Bernadette."