Sister Angelica is a young noblewoman who was forced to join a convent by her aunt, the Princess, after having a child out of wedlock. Seven years later, she has given up all earthly cares, except her love for her son, who was taken from her immediately after birth. The Princess arrives to the convent and orders Angelica to formally renounce her claim to the inheritance, since her younger sister is to be married. Angelica begs her for news of her son, and finally the Princess tells her that the boy died two years ago of a fever.
After the Princess leaves, Angelica drinks a poison to join her son in Heaven, but immediately thereafter realizes she has damned herself to Hell by committing suicide. She fervently prays for mercy. As she dies, the Mother of God, a heavenly choir and her own son greet her.
Tropes present in the opera:
- Afterlife Welcome: The Virgin Mary, a heavenly choir and Sister Angelica's son come to welcome her to the afterlife, showing that her sin is forgiven.
- Big Eater: Sister Dolcina is always longing for food. However, when she does get something to eat, she is also ready to share it with the other sisters.
- Driven to Suicide: Sister Angelica drinks a poison after learning of her son's death.
- Evil Aunt: The Princess towards Sister Angelica. Forcing a girl to join a convent after she has an out-of-wedlock child? Very harsh, but might be attributed to the the general mindset of the era. Breaking all contact with her for seven years (even though relatives are allowed to visits the nuns)? Really, really bad. Not even bothering to inform her of the child's death until two years later? Now this is beyond awful. However, she does seem to care somewhat for Angelica's sister Anna Viola, wishing her to have a good dowry, and if we are to believe her, she did all she could to save Angelica's son.
- Evil Sounds Deep: The Princess, a contralto, has the deepest voice of all and is the only actively evil character (the rest are Stern Nuns at worst).
- Meaningful Name: Angelica is a gentle, pious, helpful Nice Girl.
- Mid-Suicide Regret: After drinking the poison, Sister Angelica realizes she has committed a mortal sin and damned her soul. Thankfully, she has a bit of time to repent.
- Monochrome Casting: The opera only has female characters (except for an offstage male chorus).
- Nephewism: Angelica and her sister Anna Viola were raised by their aunt after their parents died twenty years prior to the events of the plot.
- Outliving One's Offspring: Sister Angelica learns that her son has been dead for two years.
- Together in Death: Angelica is reunited with her son in Heaven, like she longed to.
