Sister Kenna James's punishment by Mother Superior Helena Locke for reading a romance novel in chapel is interrupted by Father Tommy Pistol's need for Kenna to hand-wash his vestments. As James retreats, Pistol confronts the Mother Superior: "You're too hard on her." To which she ripostes, "You're too soft. If you spare the rod, you spoil the child." Mother Superior then lays into Sister Charlotte Stokely for giving James an advance copy of her book, to which Stokely benignly replies, "Since when is knowledge a bad thing? Change in the Church isn't going to happen unless we force it."

New bride Ashley Lane upsets Father Tommy with her historical perspective that he witness, and assist, the consummation of her marriage with Dante Colle, leading to Father Tommy's self-flagellation as penance for his lustful thoughts. When Sister Charlotte tries to comfort him, Mother Superior sends her away and then compounds his guilt, taking the flail and picking up where he left off.

Literary agent Aiden Ashley tries to get Sister Charlotte to go on a book tour, but she declines, saying, "I have a lot of work to do here." Bishop Steve Holmes, upset by Sister Charlotte's book, leans on Mother Superior to denounce and excommunicate her, then entices Father Tommy to denounce her: "Think of it as a test." And when Holmes finds out that Father Tommy has impure thoughts, he tells him about the insider track for bishops: sterilized "vestal virgins" who have taken a vow of silence to guarantee that word never gets out about pastoral indiscretions. "When you denounce Sister Charlotte, Sister Kenna can be all yours. You can also stay loyal to your friends and have no career. And I'll be happy to take on Sister Kenna myself." 

Excommunicated, Stokely says goodbye to Mother Superior, who observes that her civilian clothes make her look like a "dyke whore," calling back to their lesbian relationship. Mother Superior then throws her to the ground, beating her and blinding her with a metal rod. When agent Ashley comes inquiring after Charlotte, Mother Superior disavows any knowledge of her. "That book stirred up a lot of trouble for us, and I could care less where she is." But when Mother Superior tries to get Charlotte to atone, Charlotte's loving declarations bring out the conflict within her, and sex with Charlotte confirms Mother Superior's resolve to keep Charlotte there, silenced.

But Mother Superior isn’t finished: She recruits Sister Kenna to be Father Tommy's vestal virgin, seducing her right in front of Father Tommy. Charlotte gets Sister Kenna to help her continue her memoirs, reassuring Kenna about her guilt at the forced pleasure from Mother Superior. After Father Tommy stands up to Mother Superior ("Leave Kenna alone—I don’t want you filling her mind with your poison") she arranges for Sister Kenna to be excommunicated and sent to a cloister, offering Father Tommy two vestal virgins if he forgets about Kenna. He takes the bait as Kenna tearfully watches.

With Father Tommy compromised, Mother Superior presses her advantage, burning Charlotte's new manuscript and strangling her. When a bereft Father Tommy prays for a sign, Kenna comes to him, and their encounter emboldens her to confront Mother Superior, leading to a reckoning for Sister Kenna, Father Tommy and Mother Superior — and a hopeful postscript. 

Stokely shines as the victimized nun who keeps lovingly accepting the people who have wronged her, and Pistol is a particular standout in his performance as the conflicted priest. The dark cinematography by Matt Holder reinforces the oppressive atmosphere.