Joanna (Emily Beecham) has struggled all her life with a deep desire to give herself to God. As she's about to finish University, she suddenly announces to family and friends her intention to become a nun. Her best friend cannot believe it, her boyfriend is devastated and her mother believes it's obviously just a phase. Arriving at the convent, Joanna is soon out of her depth with the liberalism of Novice Sister Ignatious (Brenda Blethyn). Her own belief is further tested as she's introduced to more of the Sisters – a psychotic Mother Superior (Susannah York), an alcoholic football fanatic (Rita Tushingham) and an over pious floor mopper (Pauline McLynn) are only the beginning.