The true story of Leonie Martin, the "hidden sister" of St. Therese of Lisieux, who was the least gifted of the five Martin girls. She was an emotionally disturbed child who suffered much and caused anguish in her family and especially for her saintly mother, Zelie. This movie reveals the backward child who also had significant physical health issues, and yet was the first one to follow Therese's "Little Way". It was only after three valiant but unsuccessful attempts to enter religious life that Leonie was finally accepted by the Visitation Order in Caen, France. She succeeded in conquering her difficult temperament, so that by the time of her death in 1941 at the age of seventy eight, Leonie was regarded as a saint and her convent was inundated with letters testifying to her posthumous aid.