Photo: Richard Termine

What with The Book of Mormon, Mitt Romney, Jon Huntsman, HBO’s Big Love, and Jon Krakauer’s Under the Banner of Heaven, the Church of Jesus Christ of Latter-Day Saints and its fundamentalist offshoots are having a moment. Now comes Nico Muhly’s chamber opera Dark Sisters, which offers a premise in place of a plot and a score in need of momentum. It was just a few years ago that Muhly emerged on the new-music scene with a bracingly original voice. In “The Only Tune,” he put a gruesome folk song through a meat grinder of electronics. Since then, he has leaped to Establishment status with Two Boys, which opened (to mixed reviews) at the English National Opera last June and arrives at the Metropolitan Opera in two years. But in Dark Sisters, he’s tempered drama with timidity.

The librettist, Stephen Karam, has brought in an irresistible bouquet of ingredients: the gaudy southwestern desert, characters barricaded behind God-given certainties, a totalitarian paterfamilias and a quintet of powerless women, a clutch of children taken by the state. At first, Muhly savors the musical consequences of polygamy: Kevin Burdette, the cast’s lone male, anchors an iridescent counterpoint of female voices with his implacable basso. But then nothing goes properly awry. Muhly responds to the biblical clash of emotions with a string of amiable moments. The ensemble settles into Philip Glassy churning. String pizzicati, mixed with harp and celesta, produce a thin, music-box tintinnabulation. Harmonies go round and round.

Facing the bitterness of the outside world, the wives constantly repeat the mantra of the polygamist patriarchs Rulon and Warren Jeffs: “Keep sweet.” The phrase is an exhortation to banish feelings, doubts, and challenges and embrace total obedience. Muhly takes it as an instruction, too, and applies it to the relentlessly cloying score. Tempos stay moderate, dynamics hover around mezzo forte, dissonances dissipate before they can gather. In the second act, Eliza (the compelling Caitlin Lynch), the most tormented of the wives, launches into an outburst of honesty on national TV—she was a child bride, she admits, and her 15-year-old daughter is about to be married off to a grandfather. Muhly lets Eliza hang there, her words carried by music that dares only get slightly louder and a smidge thicker, but hardly more intense. For all his sensitivity, Muhly doesn’t seem to know what to do with despair—a serious liability for a composer of operas.

Dark Sisters

By Nico Muhly.

Commissioned and Co–Produced by the Gotham Chamber Opera, the Music-Theatre Group, and the Opera Company of Philadelphia.

Gerald W. Lynch Theater at John Jay College.

Through Nov. 19.