A spring evening in the garden of a convent.
Sister Angelica, the daughter of a noble Florentine family, has taken the veil in order to atone for her sin: an illicit passion when young which resulted in the birth of an illegitimate child. Seven years have passed, though she is unable to forget her son.
The strains of an Ave Maria can be heard from the convent chapel. A group of nuns emerges from the chapel after the service. The Monitress admonishes those who are late for vespers. For missing the service they will be punished and the latecomers enter the convent in order to fulfil the wishes of the Monitress.
Sister Genovieffa observes that the fountain is on the verge of turning gold from the rays of the setting sun as it always does for three evenings during May, a sign of divine grace from the Blessed Virgin Mary. A melancholy moment follows as the nuns recall a sister who died a year ago. Sister Genovieffa suggests that “Perhaps her soul might desire a libation from the fountain?” Answering her question, Sister Angelica declares that desires only come to fruition for the living – the dead have already fulfilled their earthly purpose and their destinies cannot be changed. Displeased with the theme of the conversation, the Monitress reminds them that, as nuns, all desires are forbidden to them. Sister Genovieffa begs to differ: she, for example, yearns to hold a pet lamb. And yet another sister has a wish. The nuns laughingly reply that it must be for something tasty to eat. Drawn into the conversation, to the amazement of all Sister Angelica denies wishing for anything. Their surprise is easily explained – all know that she has been craving news from her family – that same family which forced her to take the veil.
The Nursing Sister rushes in, much distressed: a nun has been stung by a wasp and is in great pain. Angelica swiftly prepares a herbal remedy. The Nursing Sister leaves, praising Angelica’s skill. Two Alms Sisters appear. They mention that a magnificent carriage with a coat-of-arms has arrived at the convent. The Abbess enters and summons Sister Angelica into the hall. Some important visitor has arrived. Before her, Sister Angelica sees her aunt the Princess. The latter exudes coolness and severity. She has come to demand that her niece sign away her share of the family heritage in favour of a younger sister. Her fiancé is willing to overlook the dishonour Angelica brought upon the noble household’s reputation. She must pay, in part at least, for her actions. Unmoved by Angelica’s protests and desperate enquiries about her son, the Princess brutally informs her that her son died two years previously.
The document is signed and the Princess departs. Grieving in the utmost despair, Angelica begs for divine mercy. The nuns proceed to their cells. Angelica follows but then returns to prepare a lethal draught distilled from herbs and flowers. Bidding a tender farewell to the sisters, Angelica swallows the poison but is suddenly overcome by guilt at having committed the mortal sin of taking her own life. Again she prays to the Virgin Mary for salvation. Her prayer is answered. Angelica’s young son approaches his mother and kisses her.