Albeit unorthodox, Francis Poulenc’s  Dialogues des Carmélites is nonetheless one of the great works of the opera repertory. It has no romantic love affair, being concerned rather with the relationships among an order of French Carmelite nuns and the family members of their newest novice. Taking place at the time of the French Revolution, the opera  treats the sisters’ arrests, and ultimately their executions. It was given a worthy performance Thursday, April 19, by Boston University’s Opera Institute and Chamber Orchestra, conducted by William Lumpkin and stage-directed by Sharon Daniels. There are further performances tonight and tomorrow at B.U.’s Huntington Theater.

Perhaps the only aspect over which more pains should have been taken was the program booklet, which had a number of errors, the most egregious being: the surname of the original historical short story’s author was listed three different ways (Gertrude von le Fort is correct); the projected English translation is by Joseph, not John, Machlis; and the nuns were certainly not arrested on June 22, 1974 but rather June 22, 1794. A reliable, independent proofreader might give all concerned more peace of mind in future.

The production conformed to the composer’s wish that his opera be performed in the language of the singers and audience, and the Machlis translation, slightly adapted from the Ricordi score, worked well. The cast’s enunciation ranged from good to excellent. A curiously unexplained credit: “Reorchestration by Tiffany Chang.” Poulenc’s special emphasis on wind instruments and his trademark sensual colors didn’t seem perceptibly altered; one wonders why the need to “reorchestrate” was felt.

On the cusp of the Revolution (1789), the opening scene contrasts with the rest of the opera, being set in the elegantly appointed library of the Marquis de la Force and largely a dialogue between the Marquis and his son, the Chevalier de la Force. The rest of the piece transpires in considerably less opulent locales (the convent, prison, etc.), and the leading characters are largely female. Bass-baritone Adrian Smith, as the calm paterfamilias, and tenor John Irvin as the son worrying about his sister, displayed attractive voices. The characters’ age difference was skillfully suggested by carriage and gestures. When the Marquis’s daughter, Blanche de la Force, appears later, she seems to justify her older brother’s concern that her lifelong condition of morbid fear and hypersensitivity is worsening. Soprano Celeste Fraser portrays this well, and her naturally rapid vibrato subtly reinforces the characterization. Her subsequent declaration to her father that she intends to enter the convent marks her first assertion of independence, yet she doesn’t seem absolutely certain of her reasons.

Some of the text here, both father’s and daughter’s, got covered by the orchestra. This recurred later a few times. Usually, the surtitles would be there to fill in any gaps, though they were somewhat erratic.

At the convent Blanche is then interviewed for admission to the Carmelite order. As the old, ailing Prioress, Madame de Croissy, mezzo soprano Amanda Tarver, though not the contralto Poulenc specifies, has sufficient gravity of character and low notes to be convincing. Her manner while questioning Blanche alternated between gently welcoming and brusque. The mood is lightened later when now-Sister Blanche and her fellow novice Sister Constance do chores together. Constance is a flighty type, and soprano Sonja Krenek gave her an amusing chatterbox persona. Speaking irreverently of the Reverend Mother, she feels, “… if I could save the life of our dear Mother, I would gladly surrender my poor little life … But really, at 59 years, is it not high time to die?” This elicited some uneasy titters! Though friends, the two novices have very different outlooks and at this point fail to have a meeting of the minds.

Act I ends with Madame de Croissy’s extended death scene, beginning with the touching devotions of Mother Marie, soprano Lauren Ashleigh Lyles, to the Prioress who entrusts Blanche to her care. Here too, unfortunately, there were a few text audibility problems. The Prioress summons Blanche for a personal farewell since, as the most recent novice, Blanche is closest to her heart. A string of high pppp orchestra chords announcing the novice’s arrival might have been a ravishing moment but for the painful intonation. Nonetheless, the final conference of “mother and daughter” was a very moving, powerful blend of expressive singing from Tarver and Fraser, containing acting that rang true and the beautiful colors of Poulenc’s accompaniment. However, Act I ends with the Prioress passing into delirium — something not far from a mad scene — and expiring in harrowing fashion.

Early in Act II, Mother Marie is essentially acting Prioress; she follows the example of the late Prioress, treating Blanche with alternating asperity and tenderness. Marie is quick to realize that the community is looking to her for authority, and Lyles’s firmness of voice and gesture is telling as she interacts with Blanche. A new Prioress, Madame Lidoine, arrives to make her long inaugural speech to the sisters. Meredeth Kelly’s large, handsome soprano voice is certainly integral to her characterization of the new leader taking charge. She leads the Carmelites in a setting of Ave Maria, sung exquisitely by Kelly and the nuns’ choir.

Later the Chevalier comes to the convent in an attempt to persuade Sister Blanche to come home with him, feeling she would be safer there during these troubled times. There is a painful debate, and Irvin and Fraser make clear that while her brother understands her better than their father does, he still thinks of his younger sister as a little girl depending on her family for protection. For the first time, Blanche asserts her adulthood and independence, but her brother almost short-circuits it by using her early pet name, “little rabbit.” Fraser endows her with new strength, but plainly her vulnerability hasn’t altogether disappeared. Irvin also seizes his opportunity to show new layers of the Chevalier’s personality. For the first time he is made to see his and the Marquis’s over-protectiveness of Blanche, and though he may be open-minded enough to perceive his mistake, he is unable to do an immediate emotional about-face and admit it openly. His exit is emotionally ambiguous–not something one is likely to see in conventional operas. The singing and acting were equally impressive here.

As Act III opens, in 1794, the Carmelites, long since expelled from their convent, clandestinely reunite there in secular garb. Blanche has been forced into servitude in her family’s house and has had to watch her father’s execution, but her instinct for self-preservation has strengthened. When Mother Marie arrives to bring her back to the convent, she is reluctant, feeling better hidden as a menial at her childhood home. Fraser delicately walks the line between reluctance and outright disobedience; Lyles supplies an electrifying moment when she suddenly, dramatically addresses Blanche using her chosen Carmelite name, Sister Blanche of the Agony of the Christ.

Naturally, the nuns are discovered in their convent and arrested. Having no illusions, the new Prioress joins them in their pledge of martyrdom. Kelly floated some beautiful pianissimo high notes, telling her daughters that even Christ had a moment of fearing death. Sister Constance offers her opinion that Sister Blanche will return, and when asked how she knows, hesitantly explains that she had a dream. In the score the sisters burst out laughing, the last moment of comic relief, but here all remained grim. Perhaps this was to intensify the foreboding just before the jailer arrives to confirm that they are all indeed condemned to die. If so, such was achieved.

The final, very famous scene depicts the sisters mounting the scaffold one by one while they all sing the Salve Regina. The guillotine sound effect began almost subtly but became increasingly powerful as the scene progressed and the nuns’ choir shrank one voice at a time. The gathered crowd, initially a rowdy rabble, becomes strangely quiet, impressed by the serene fortitude of the Carmelites. The wordless mixed chorus evocatively filled out the harmonies of the nuns’ hymn. Sister Constance appears to be the last to die, but as she starts toward the scaffold, Sister Blanche emerges from the crowd; there was a profoundly moving moment as the sisters smiled at each other, each reinforcing the other’s resolve in a silent pledge of eternal friendship. After Constance’s singing is cut short, the crowd starts to go home. Blanche, in secular clothes, could do the same but chooses to reveal herself by singing the Veni Creator and walking to the scaffold. The silence when her song ended was haunting. There is a very brief and quiet orchestral coda. The audience sat in stricken silence as the curtain slowly descended, but then burst out in hearty applause. The few shortcomings, largely audibility issues, should be addressable while the singing, acting, and staging went from strength to strength. For those who love this work and those who have yet to encounter it, this is a production you shouldn’t miss.