Appointed Mother Superior in a remote Irish nunnery, Mere Helene realises she has to save her star student from the regime she herself has until now espoused.
As three postulant nuns receive the veil at the school of Sainte Famille, the Reverend Mother recalls how at 18 she herself had turned her back on the world.
As six-year-old Anna Murphy comes to terms with her first few weeks at the convent school, the Reverend Mother begins a letter of resignation to the Mere Generale.
The Reverend Mother has found remarkable qualities in Anna Murphy, her newest and youngest pupil, that remind her of herself when young.
Young Anna discovers that the school is rife with gossip, snobbery and vindictiveness.
On the night that she learns that her father is dying, Reverend Mother recalls the event that drove her to turn her back on the world.
Summer holidays have arrived at last, but financial imprudence has begun to take its toll on Anna's parents' marriage.
On the annual family holiday in the summer of 1913, Anna's brother Charlie is drowned in the local harbour.
Anna's formidable grandmother wants her to forego her hard-won scholarship and work in a bank.
Mere Helene has other ideas.
A telegram from the Mother House in Brussels presents Reverend Mother with the biggest challenge of her life.