This compelling drama unfolds during the transformative period of Vatican II (1962-65) within a Catholic convent, as experienced through the lenses of various characters including the stern, traditional Mother Superior and the more compassionate, modern nuns, along with the Postulants and Novices—especially focusing on Sister Cathleen.
In 1954, young Cathleen Harris (originally played by Eliza Manson) resides in rural Tennessee alongside her mother, Nora (a factory worker disinterested in religion), who wishes to expose her daughter to church and allow her to make her own choices. Cathleen's father, Chuck (portrayed by Chris Zylka), returns home inebriated one night, which leads to a heated argument with Nora, resulting in his departure. Left to fend for herself, Nora cycles through a string of fleeting relationships.
At the age of 12, Cathleen (played by Sasha Mason) longs for affection and finds solace in Catholicism after two nuns visit her family and propose she enroll in a Catholic girls' school, offering her a scholarship contingent on her stellar academic performance. During her time at school, a young nun becomes a friend to Cathleen, conveying her own unique relationship with Christ. Fast forward to 1964, after encountering yet another transient partner of her mother, Cathleen (now Margaret Qualley) decides to depart her troubled home environment and dedicate her life to God.
She becomes a postulant among twenty other girls at the Sisters of the Beloved Rose. The path ahead is filled with challenges and discipline under the watch of Reverend Mother Marie Saint-Clair (played by Melissa Leo), a tough and unyielding figure who imposes strict training measures and harsh penalties during the weekly "chapter of faults" sessions. During these sessions, the postulants confess their wrongdoings and often endure humiliating penances like "The Discipline," a knotted whip used for self-flagellation.
Contrasting the Reverend Mother, Sister Mary Grace (played by Dianna Agron) is a kind-hearted and open-minded nun that seeks to ease the burdens of the postulants. Though life in the convent is predominantly regimented, fleeting moments of camaraderie and laughter emerge among the sisters. However, Cathleen often shies away from her peers, preferring solitary moments immersed in scripture.
Amidst this structured environment, the Reverend Mother ignores letters from Archbishop McCarthy regarding Vatican II. When Sister Mary Grace advocates for the necessity of change, she is sharply rebuffed by the Mother Superior, who insists, > “The Church is perfect exactly the way it is.” Their disagreement stirs tension, culminating in Sister Mary Grace's decision to leave the convent.
After completing her postulancy, Cathleen takes her Simple Vows and becomes a novice. As the Reverend Mother's demeanor turns increasingly austere, Cathleen begins to grapple with an awakening of her own sexuality. One night, after awakening from a confusing dream, she withdraws further into herself, plagued by feelings of guilt and shame which impact her physical well-being. During a visit from her mother, Cathleen appears frail and malnourished, prompting Nora to confront Reverend Mother about her daughter's suffering. The Reverend Mother dismisses the concern, remorselessly stating that Cathleen is now entirely devoted to the Church.
Cathleen ultimately faints during dinner due to starvation and is confined to the infirmary, where she confides her struggles to Sister Emanuel (Rebecca Dayan). In a moment of vulnerability, Cathleen and Sister Emanuel share an intimate encounter, which leads Cathleen to find a sense of peace. Following this episode, Cathleen starts to show signs of recovery, but the two women never revisit their passionate moment.
As the narrative progresses, Archbishop McCarthy visits the convent, informing the Reverend Mother that the order must transform in order to survive the reforms initiated by Vatican II. He warns her that failure to adapt might result in her replacement. The news sends the Reverend Mother into despair, fearing her connection with God has been severed.
In a subsequent chapter meeting, a novice shares her doubts about God's existence, prompting an unusually lenient response from the Reverend Mother. When Cathleen confesses her need for emotional comfort and her past with Sister Emanuel, she is forced to humiliate herself before her peers as a form of penance—this ultimately leads to her emotional breakdown. Afterward, Sister Emanuel slips away from the convent without bidding farewell to Cathleen.
Eventually, in a dramatic congregation meeting, the Reverend Mother unveils the Archbishop's directives surrounding Vatican II changes including the use of English during Mass and encouraging religious tolerance. This marks a shift in the status of nuns, as they are no longer mandated to wear traditional habits.
Among the original twenty postulants, merely five remain to take their final vows, with Cathleen among them. During the solemn mass for their Profession, when asked what she seeks, one novice answers that she wishes to marry Jesus Christ. When it's Cathleen's turn, she decisively asserts, > "I seek something more."
