Mere Marie-Helene once turned her back on life, sealing up her heart in order to devote herself to God. Now the formidable Mother Superior of an Irish convent, she has, for some time, been experiencing grave doubts about her vocation. But when she meets Anna Murphy, the youngest-ever boarder, the little girl's solemn, poetic nature captivates her and she feels 'a storm break in her hollow heart'. Between them an unspoken allegiance is formed that will sustain each through the years as the Reverend Mother seeks to combat her growing spiritual aridity and as Anna develops the strength to resist the conventional demands of her background.