The end of the 1950s, on the outskirts of Brussels.
Like the rest of the young generation of the time, Jeannine Deckers (Cécile de France) has a thirst for freedom and adventure. There's no question of her following the path her parents have chosen for her - finding a husband and taking over the family bakery. She wants a different life. To move away, to meet other people.
After toying with art studies, she enters a convent. Jeanine finds out that being a Dominican nun is a difficult vocation. It requires giving up one's passions, including music. But she's not
prepared to do this. The other sisters don't understand her, but with the blessing of the Mother Superior, she sticks to her dream and writes a global pop hit: 'Dominique'.
For audiences around the world, Jeannine became 'Sister Smile', also known as the Singing Nun. She was a worldwide sensation and sold millions of records. Her success was compared to that of Elvis Presley.
Struggling to reconcile her faith and her newfound fame, Jeannine leaves the convent and attempts to continue her career as a rock star.
The film traces the unique and deeply moving story of this young girl who never gave up.