When Maude Maggart, whose three-week run at the Oak Room opened Tuesday, first began performing around New York a few years ago, she was a distinct novelty: Not many women in their mid-20s could expertly sing Irving Berlin songs from the mid-’20s. Even fewer could deliver the requisite in-between-tune patter, when performers talk about the songs as if they really know and love them and understand the era that produced them. Since Ms. Maggart opened the door, any number of young chanteuses have paraded their wares in the Algonquin, including 19-year-old Samantha Sidely and, last month, 16-year-old Judy Butterfield.

Ms. Maggart never traded on her precociousness, yet it couldn’t help but serve as a factor in her past performances: Her deliberate attempt to evoke like a supperclub chantootsie of the pre-war era went beyond simply wearing a glamorous gown and jewelry. As good as she was — and still is — there was always something about her that reminded me of a debutante at her own coming-out party. With her new show, “Good Girl/Bad Girl,” a well-conceived production that places her as a successor to Mary Cleere Haran and Andrea Marcovicci — the big-leaguers of deepcontext cabaret — Ms. Maggart finally seems ready to compete with the grown-ups.

In fact, Ms. Maggart, now 30, addresses the topic of maturation as an opening and closing idea for her new show. She bounced in wearing a bright red evening dress, the necessary costume for “How Could Red Riding Hood?” This double entendre song from 1926 speculates that the heroine of the fairy tale “kept the wolf from her door” by doing something rather more carnal than shlepping a basket to Grandma: “They say that she found a wolf in Granny’s bed … but you know and I know what she found instead!”

For the next hour or so, in monologue and in a dozen other songs, Ms. Maggart examined the duality of moral relativism as it’s addressed in the popular song, not in an academic fashion, but in a way that’s hip, smart, sexy, and highly entertaining. The tale of Red Riding Hood has been transformed into adult entertainment with a salacious twist; contrastingly, Joan Baez’s “Love Song to a Stranger,” in which she sings of sleeping with someone she hasn’t been properly introduced to, is much more explicit. Ironically, although Ms. Maggart has often told audiences that she rarely listens to music made after 1930, it turns out that she excels at delivering latter-day story songs with folkish melodies and an involved narrative.

On the subject of marriage, she summoned two pieces of contrasting evidence: Jerome Kern and Oscar Hammerstein’s “Folks Who Live on the Hill,” which depicts a union of two people in an exalted state, vs. “Marriage Is for Old Folks.” She sang the first optimistically but not naïvely, and she is one of the few performers of the 1936 tune who sings like she knows who “Darby and Joan” are. She did the second, originally rendered by Nina Simone as a swinging waltz, with more of a folk-blues feeling, replete with squealing high notes. She also played two Richard Rodgers songs against each other, and surprisingly, the relationship is idealized in the text by Lorenz Hart on “He Was Too Good to Me,” whereas the couple in Oscar Hammerstein’s text to “What’s the Use of Wonderin’,” is clearly dysfunctional. One would expect it to be the other way around.

As a singer, Ms. Maggart has a small voice with a quavery vibrato, but she knows well how to work within her limitations, and has the smarts to stay within her range. Her singing is not so much about melody or rhythm as it is about heart and feeling. I’ve heard the well-known Helen Kane record of “I Want To Be Bad” — which expresses an ambition for wickedness in the most innocent way imaginable — many times, but Ms. Maggart is the first performer who makes me understand the line “give a damsel credit,” with a telling pause in between the two syllables of the word “damsel.” (Thankfully, Ms. Maggart omits Kane’s interjection of “boop-oop-a-doop.”)

She concluded with another update on the Red Riding Hood story — Stephen Sondheim’s “I Know Things Now” (from “Into the Woods”), a song that also uses the image of being eaten by a wolf as a metaphor for the passage into adulthood. Ms. Maggart revels in her state of having made the transition and acknowledges that something beautiful has been left behind in childhood: “Isn’t it nice … and a little bit not.” Clearly, this is one Dorothy who’s not in Kansas anymore.

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The late Screamin’ Jay Hawkins, that scariest of all great R&B stars, customarily made his entrances to his theater shows in a coffin, belting and screeching out the words to his signature theme, “I Put a Spell on You,” which he accentuated with a sinister, Bela Lugosi-style chortle. When the rapper and pop star Mos Def sang it in a similarly theatrical style to open his own concert Wednesday, he paraded down the steps of the Allen Room, flanked by the eight members of the Hypnotic Brass Ensemble, all hooded so they looked like druids, and joined the rhythm section onstage. Hawkins’s famous baritone sax vamp was essayed by a combination of tubas and trombones, pumping back and forth with wild energy.

Mos Def is the third pop celebrity to be presented out of context in the Allen Room in recent months (following Sting doing Renaissance lute music and a Willie Nelson-Wynton Marsalis collaboration) as the opening salvo of the new season of Jazz at Lincoln Center’s American Songbook. He has already proved that, although hiphop is his home base, he can capably sing blues and rock classics and generally do more than just come up with rhymes for the word “bitch.” Much of what he sang and said was unintelligible, though I did recognize more four-letter words than I have ever heard at Jazz at Lincoln Center.

As it happens, there are a lot of first-rate singers working in New York this weekend. In addition to Maude Maggart at the Oak Room, there’s Rene Marie at Dizzy’s, and the legendary, 85-yeard-old original rapper Jon Hendricks at Birdland. But I will wager none of them will be quoting Tony Kushner before segueing into an irreverent deconstruction of “Of Thee I Sing” and “The Star Spangled Banner” in an obvious reference to the famous line regarding the Anthem in Mr. Kushner’s “Angels in America.” Almost any kind of music, even rap, sounds better with acoustic horns, and even though it was hardly my usual kind of thing, I have to admit that Mos Def put a spell on me.

wfriedwald@nysun.com