In early 1858, at the Massabielle grotto, 14-year old asthmatic, illiterate miller's daughter Bernadette sees a light she later distinguishes as a beautiful young woman. The girl and the woman converse over the next few months. Crowds follow and people are cured by the waters from a spring Bernadette has cleared. Secular authorities are threatened by the popular gatherings and subject the girl to inquiry and medical review. The local monsignor, initially skeptical, becomes Bernadette's champion. She maintains her forthright simplicity and untutored wisdom throughout.

Chronicles Bernadette's years with the Sisters of Charity of Nevers convent, from age 22 until her untimely death from tuberculosis at age 35.