Ellen Christenson was on vacation, sitting in a Southern California movie theater with her son and watching the Coen Brothers’ O Brother, Where Art Thou? unreel. "We were enjoying the movie and the music and this song comes up, quietly at first, because the actors are talking. And I thought, ‘That sounds awfully familiar.’ And then the singing got louder, and when I realized it was us, I practically fell off my chair."

The "us" is Ellen and her sister Irene Saletan, and the song is the Appalachian folk hymn "I’ll Fly Away," which Irene and Ellen recorded on their first and only album in 1956, when they were just 17, and performed under their maiden name as the Kossoy Sisters.

"When we got out of the theater, I grabbed my cell phone and called Irene. That was on a weekend, so the next Monday I called Ryko, which had reissued our album, and they said, ‘Oh, did they finally use that?’ Ryko was just totally screwed up at the time. They hadn’t even bothered to print more copies of the album, so it was out of print right after the movie came out. Ryko was with Palm Pictures then, and nobody there knew anything, you couldn’t talk to anyone. They weren’t interested in us at all because we weren’t making lots of money for them."

The next stop was a record shop, where the sisters discovered that country artists Alison Krauss and Gillian Welch had recut "I’ll Fly Away" for the film’s soundtrack album. That was disappointing, as was the flat fee they received for their performance’s use on screen. But it was a spark, and now the sisters — who are retired from their day jobs and living in Boston — are fanning the flames of their musical career. Ryko has once again reissued Bowling Green by the Kossoy Sisters with Erik Darling as part of its series of titles that were originally recorded for the esteemed folk label Tradition; the difference this time is that Ryko is once more an independent, having extricated itself from Palm Pictures’ corporate web in New York City, returned to Boston’s North Shore, and relocated in Gloucester. ("Now they’re a dream to work with," says Irene.) And the sisters have not only resolved to return to regular performing but have finally — after 46 years — made their follow-up to Bowling Green.

It’s not just the Kossoys’ close harmonies — which have the breathtaking doppelgŠnger impact that helped make country-music sibling teams like the Louvin, Wilburn, and Whitstein brothers spellbinding — that are striking about Bowling Green. It’s the idea that two teenage girls from Queens could re-create the music that echoed through the hills of the rural South decades earlier in such a convincing, mournful, and lovely manner. Many of the songs fall into that category of American folk music called murder ballads. Singing against their spare guitars and accompaniment from Darling’s banjo and guitar, Irene and Ellen blithely harmonize through a killer’s first-hand account of stabbing and drowning his sweetheart in "The Banks of the Ohio." And they cheerily negotiate the opening of "Poor Ellen Smith": "Poor Ellen Smith, how was she found/Shot through the heart lying cold on the ground/Her body was mangled and cast all around/And blood marks the spot where poor Ellen was found."

The chipper tone in which they spin such grisly tales seems just an irrepressible extension of their personalities. When we meet at the 1369 Coffeehouse in Cambridge’s Inman Square, I find them to be infectiously upbeat, two good-natured sparkplugs with mile-wide smiles. They’re also extremely identical twins who finish and amplify each other’s sentences with the same natural comfort that buoys their harmony singing. They’re so alike, even their taste in haircuts is similar, and when they step to the counter they both order lemonade. As the attendant eyes them, he yells to the back room, "Hey, we’ve got twins!", and the kitchen man comes out, stares, and quietly goes back. The sisters share a glance and smile.

"There’s something very satisfying about singing those songs," Irene says after we sit down. "They’re often the same stories as the old British ballads, but the American ones go right into blood all over the room."

They explain that they were born in the Bronx and moved to Queens with their mother and an older sister when they were five, after their father died. Their mother’s sister, who played the piano, also moved in. And their mother and aunt often sang, inspiring them. " ‘You Are My Sunshine’ was the first song we ever harmonized together," says Irene. "When we first discovered we could do it, we were so excited that we just started singing it over and over, then trying it with other songs."

At age 15 the sisters got even more excited about music when Pete Seeger and other folk performers visited the summer camp they attended. Soon they were hanging out in Washington Square Park, where Mike Seeger, Mary Travers, Ralph Rinsler, and members of the New Lost City Ramblers congregated to swap songs. They began their schooling in American and British folk music, and they developed their early repertoire of about 100 numbers. The sisters were asked to record Bowling Green after they’d begun performing at hootenannies and concerts around Greenwich Village; for the album they recruited Darling, whom they’d also met in Washington Square.

"Things were much less complicated then," says Ellen. "This is before Joan Baez and Bob Dylan were around. You kind of knew everybody who was playing the music. When we recorded our album, we did it in a studio in one afternoon."

By the time Bowling Green was issued, Irene and Ellen were enrolled at Blackburn College in Illinois. They continued to perform; they were even featured at the first Newport Folk Festival. After graduation they went their separate ways — Irene to St. Louis and Ellen to Boston — and embarked on their individual lives, working, raising families, and occasionally uniting to play festival or club dates. Three years ago, when Irene retired, she moved to Boston to be closer to Ellen and to resume musicmaking in earnest.

Early next month the Kossoy Sisters plan to release their new album, Hop On Pretty Girls (Living Folk); in the process they may well set a record for the number of years between a debut and its follow-up. "It’s mostly traditional and mostly us doing harmony," says Irene, "but the accompaniments are a little more sophisticated, a little tighter. There’s a Carter Family song, Woody Guthrie songs, one I wrote and one Ellen and I wrote together." The CD should be available just in time for their appearances at the Cambridge Center for Adult Education on November 8 and 9. (Call CCAE at 617-547-6789.) "Thanks to the movie," Ellen says, "more people are finding out about us, and we’d like to perform more around here and do a little bit of touring."

You might also see Ellen at the New England Aquarium, where she helps tend to the penguins as a volunteer, or run into Irene walking dogs for the Animal Rescue League — though they’re easier to recognize, if not tell apart, when they’re together.

BILL MONROE, the father of bluegrass, was a stern man. He would not have approved of the Benders singing about scoring little bags of heroin, twisting his straight-spine music to fit their vision. He’d have had no trouble with the band’s contemplation of murder, "Donna Lee," but that’s another story. This one is about how the Benders have harnessed the spirits of bluegrass and punk rock, playing gigs hereabouts primarily at Somerville’s Tír na n-Óg and now releasing their second CD, The Benders II (Pig Pile).

"Bluegrass has some pretty rigid rules about rhythms and things of that nature," says head Bender Bow Thayer by phone from his home in rural Gaysville, Vermont — New England’s equivalent of Monroe’s Kentucky hill country. "It just happens that everyone in the Benders is from the Northeast, and I think there’s a certain edginess we bring to the music. Plus, most of us are from a rock background. And I don’t see a line between any kind of music. Punk rock is the same as bluegrass. You have music that has soul or it doesn’t."

For the Benders, soul seems to arise from a blend of traditional acoustic sounds — Thayer’s banjo, Jabe Beyer’s guitar, Nolan McKelvey’s bass, Tim Kelley’s dobro, and Sean Staples’s mandolin — and modernist attitude, though between the lines of cynicism and humor blows the dust of long-time folk-song themes like love, betrayal, and retribution. Thayer brings a simple, direct sense of melody to his banjo playing that’s offset in particular by Kelly’s elegant dobro. The boldness of Thayer’s lines may be a legacy from his past as a guitarist in Seven League Boots and the hick-rock outfit Elbow; he also admits to incorporating blues licks copped from Fred McDowell and John Hurt records into his picking.

The Benders started as a back-porch jam session among friends who now occasionally reconvene to make albums and perform. Like their debut Pig Pile CD, The Benders, The Benders II was recorded live to tape, and the fine playing and low-key vibe of both discs attests to their musicianship. As the new album seeps into stores and builds Internet sales (at www.pigpilemusic.com), the Benders will be trying to broaden their base this fall, gigging in New York and upstate Vermont and then returning to Boston. This summer they played their first shows on Cape Cod.

Meanwhile, Thayer reports that the CD is "just flying off the shelves" at the Driftwood Trading Post in Gaysville. That’s the old general store that his girlfriend and his record label’s owner just bought. "It’s about the only building around here, along with the house we live in. And they play the record all the time. The tourists come in, hear it, and buy it. I guess it might just be because this music sounds so good in this part of the country."

The Benders play a 21-plus Halloween Party on Thursday October 31 at the Dilboy VFW, 371 Summer Street in Somerville’s Davis Square. Call (617) 666-8794.