Father Flynn gives a sermon using the parable of a lone sailor who loses sight of the stars and begins to doubt his course.

Sister Aloysius warns Sister James to be more suspicious of students and less innocent in her approach to teaching.

Sister Aloysius asks Sister James to stay alert and watch for anything unusual happening at the school.

Father Flynn addresses his basketball students about how the danger of missing a foul shot is entirely psychological.

Sister James reveals that Donald Muller returned from a private meeting with Father Flynn smelling of alcohol and looking frightened.

Sister Aloysius decides to confront Father Flynn directly and insists Sister James must be present as a witness.

Sister Aloysius, Sister James, and Father Flynn meet under the pretense of planning the school's Christmas pageant.

Father Flynn claims he privately confronted Donald about sneaking altar wine to protect him from losing his altar boy role.

Sister James is relieved by Father Flynn's altar wine explanation and begins to believe he is telling the truth.

Father Flynn preaches a sermon comparing gossip to scattered feathers that can never be gathered back once released.

Father Flynn meets Sister James in the garden and argues that Sister Aloysius is trying to destroy his spirit of compassion.

Sister James tells Father Flynn she believes him.

Sister Aloysius meets with Donald's mother, who refuses to take action and fears her husband would harm Donald if a scandal erupted.

Sister Aloysius tells Father Flynn she has spoken to a nun at his former parish and demands he request a transfer.

Sister Aloysius confesses to Sister James that she lied about contacting Father Flynn's former parish, then breaks down crying about her doubts.

Father Flynn opens the play with a sermon about navigating uncertainty, setting the tone for the conflict to come. Sister Aloysius grows suspicious of Father Flynn's private relationship with Donald Muller and resolves to confront him directly. During a meeting framed around the Christmas pageant, Father Flynn defends himself by claiming he privately handled Donald's theft of altar wine. Sister James accepts this explanation, but Sister Aloysius refuses to let the matter rest and meets with Donald's mother, who refuses to take action. Sister Aloysius ultimately pressures Father Flynn into requesting a transfer by falsely claiming she contacted a nun at his former parish. The play ends with Sister Aloysius's shocking admission that she has been consumed by doubt all along.

The central investigation into Father Flynn's conduct.

Sister James visits Sister Aloysius's office to check on student William London, who was sent home with a nosebleed.

Sister Aloysius tells Sister James that William London's nosebleed was most likely self-inflicted.

Sister Aloysius chastises Sister James for being too enthusiastic and performative in her approach to teaching.

Sister Aloysius tells Sister James that Sister Veronica is going blind and asks that the condition be kept secret.

Father Flynn warns his basketball students about dirty fingernails, recounting a childhood friend who died of spinal meningitis.

Sister Aloysius reveals to Sister James that she was once married and became a war widow before taking her religious vows.

Sister Aloysius describes Monsignor Benedict as oblivious to the school's problems and therefore unable to handle the situation.

Sister James tells Sister Aloysius that Father Flynn has been Donald Muller's protector ever since Donald joined the altar boys.

Father Flynn tells Sister Aloysius to bring her suspicions about Donald to Monsignor Benedict during their Christmas pageant meeting.

Father Flynn states that a man named Mr. McGinn witnessed Donald drinking the altar wine and can corroborate his story.

Sister Aloysius calls Donald Muller's parents to request a meeting after her confrontation with Father Flynn.

Sister James tells Father Flynn she sees Donald every day but no longer trusts herself to judge how he is doing.

Mrs. Muller tells Sister Aloysius that Father Flynn is the one man who has shown genuine kindness to her son.

Father Flynn calls the bishop after Sister Aloysius demands he request a transfer away from St. Nicholas.

Father Flynn is promoted to pastor at St. Jerome's Church and School following his transfer from St. Nicholas.

The play opens with small but telling exchanges: Sister James checks on an ailing student while Sister Aloysius reveals her sharp, suspicious worldview and her hidden personal history as a war widow. Father Flynn's character is further developed through his basketball lecture, which blends practical advice with veiled commentary on doubt and vulnerability. Sister James reports what she has noticed about Donald Muller, and Sister Aloysius dismisses the church's male hierarchy as too oblivious to act. During the Christmas pageant confrontation, Father Flynn names a witness who can support his alibi and deflects Sister Aloysius's accusations with apparent confidence. After the confrontation, Sister Aloysius contacts the Muller family, and Mrs. Muller defends Father Flynn as the only caring adult in her son's life. Father Flynn ultimately calls the bishop, accepts a transfer away from St. Nicholas, and arrives at his new parish with a promotion.

The supporting characters and secondary conflicts that shape the drama.

Sister Aloysius questions Sister James about the deeper meaning of Father Flynn's opening sermon, hinting at her underlying concerns.

Sister Aloysius learns Donald Muller is the school's first and only African-American student and worries his isolation makes him vulnerable.

Sister Aloysius declares that church hierarchy parameters protect Father Flynn and they must take action entirely on their own.

Sister Aloysius tells Sister James that taking a step to address wrongdoing is a step away from God but remains in His service.

Father Flynn and Sister James push to include a secular song in the Christmas pageant, directly clashing with Sister Aloysius's rigid standards.

Sister Aloysius argues that working-class parishioners trust the clergy to remain separate and different from ordinary people.

Father Flynn becomes visibly defensive and objects to Sister Aloysius's tone during the Christmas pageant confrontation.

Sister Aloysius accuses Sister James of choosing to believe Father Flynn simply to have her peace of mind restored.

Sister James tells Father Flynn about her recurring nightmare in which she looks into a mirror and sees only darkness.

Father Flynn accuses Sister Aloysius of being the kind of person who destroys compassion and kindness in the name of virtue.

Sister James confesses to Father Flynn that Sister Aloysius has taken her joy of teaching entirely away from her.

Mrs. Muller warns Sister Aloysius that going against a man in robes is futile because of his institutional position and authority.

Sister Aloysius reveals to Father Flynn that her very first suspicion arose when she saw him touch student William London's wrist.

Sister James asks Sister Aloysius if she ever found proof of wrongdoing; Sister Aloysius admits she had only her own certainty.

Donald Muller is heartbroken by Father Flynn's departure from St. Nicholas, while Sister Aloysius dismisses this by saying it is just until June.

From the very first scene, Sister Aloysius begins probing Father Flynn's intentions by questioning the meaning of his sermon, revealing her suspicious nature before any accusation is formally made. As she learns of Donald Muller's racial isolation and vulnerability, she declares that the church hierarchy will not protect them and that she must act outside of it. The confrontation over the Christmas pageant becomes a battle of wills, with each side exposing the other's blind spots, motivations, and contradictions. Sister James is pulled in both directions, confessing to Father Flynn her nightmare of seeing only darkness in the mirror before ultimately choosing to side with him over Sister Aloysius. Mrs. Muller's warning that no woman can prevail against a man in robes underscores the power imbalance Sister Aloysius has fought throughout her entire campaign. In the final scenes every illusion is stripped away: Sister James asks for proof that never existed, and Sister Aloysius's apparent triumph is undone by her devastating confession of doubt.