At the end of the 1950s, in the vicinity of Brussels.
Like all the other young people of her time, Jeannine Deckers thirst for freedom and discovery. No way will she blindly accept the choices her parents have made for her: To find a husband and take over the family bakery. She aspires to another kind of life, imagines traveling, reaching out to people. Initially attracted to design studies, she finally enters a convent. Here Jeannine discovers that being a Dominican nun is a difficult vocation. One must renounce all worldly things, especially music. The latter is too much to ask. In spite of the other sisters' incomprehension, and with the support of the Mother Superior, Jeannine holds good and composes a Dominican "hit". Jeannine then becomes known, by the whole world, as "Sister Smile."
She becomes famous and her record sells millions. Her success will be compared to that of Elvis Presley.
The film recounts the singular and moving story of this young woman who never gave up.
