NO SIN? Krista River was a treat as Anna I.

MY FIRST ENCOUNTER with the chamber-opera group Intermezzo was a disappointment: the opera, a new commission, was a musical and dramatic dud about the complex relationship between French poets Paul Verlaine and Artur Rimbaud. And for half an hour, my second encounter was equally unsatisfying. This time the bad opera was Seymour Barab’s 1957 one-acter, A Game of Chance, a negligible morality tale about three women who yearn, respectively, for money, fame, and love. A mysterious figure arrives to give them what they want. But it doesn’t make them happy. The end. Barab owes more than he should to Leonard Bernstein’s 1952 Trouble in Tahiti, and a couple of years later, Samuel Barber showed them all how to do it with his inspired Hand of Bridge. Stage director Kevin M. Kline and designer William Fregosi placed the action, as company director John Whittlesey put it, in a "Donna Reed kitchen." The singers — Jane Eison, Sarah Davis, Sarah Whitten, and Christopher Hutton — fulfilled Barab’s requirements but wasted their time learning this vacuous material. Pianist Stephen Yenger played better than the music deserved.

The second part of the bill, however, was a great work: Kurt Weill & Bertolt Brecht’s 1933 mock morality play and Passion parody Die Sieben Todsünden, done in English as The Seven Deadly Sins. Two sisters, sharing one name, one heart, and one bank account (only one sings, though), set out across America to make their fortune so they can support their greedy and dysfunctional family in the mythical state of Louisiana. They learn that Gluttony is bad because it’s harder to sell your body if you’re overweight. ("There’s no market for hippos in Philadelphia," as the translation by W.H. Auden and Chester Kallman puts it.) Lust is bad only if you spend your capital on the person after whom you lust.

Marc Astafan’s fluid, inventive staging fleshed out the characters, adding the spice of a little father-son incest (daddy Whittlesey likes to sit his hunky number-one son, Brendan Daily, on his lap) and even a music lesson (mommy, full-bearded Paul Guttry, makes son Aaron Sheehan — Intermezzo’s pouty Rimbaud — sing for his supper, oratorio style). The two Annas, Beckett-like, arrive inside steamer trunks. The cast was remarkably efficient changing the minimal sets. Not only could they all sing well (though Catherine Lee, as the sullen, speaking Anna, didn’t have to), they also created vivid if sometimes appalling figures. Auden and Kallman make everyone work to get their English across; here the diction was exemplary.

And mezzo-soprano Krista River, from Emmanuel Music, made a stunning Anna I. This part doesn’t have to be sung beautifully to work, and it often isn’t. But River’s luscious voice was a treat. She injected words with both meaning and nuance. And she moved on stage as if she’d lived there all her life. James Busby supplied a riveting piano accompaniment, and even if everyone else had been terrible, his playing alone would have brought this scintillating, seductive, scary score to life.