This coming month will see another homecoming for Boston-area native Eric McDonald, a musician with a lengthy and diverse portfolio, when he appears as part of Celtic roots trio Kalos on Sept. 3 at Club Passim in Harvard Square.

McDonald’s homecomings aren’t exactly few and far between: He was in town back in early July, playing with the quartet Cantrip at The Burren’s Brian O’Donovan Legacy Series, for example, and in the spring of 2023 with Kalos at Club Passim. He has also regularly appeared at the annual BCMFest. 

That’s how it is when you’re a top-grade guitarist, mandolinist, and vocalist who plays with lots (and lots) of people, especially including those in the Irish/Scottish/Celtic vein: Chances are you’re going to get your share of gigs in Greater Boston.

“Coming back to the Boston area is always special for me,” says McDonald, who grew up in Newton and Medford and now lives just outside Montreal with his wife and their young daughter. “This was where I met so many people, and had so many experiences and opportunities that were important in my becoming a musician. So much of my involvement in music was social: My friends played music, so I did, too, and it was all a load of fun. I have great memories of those times.”

Besides Kalos – a Greek word that connotes the classical idea of “beauty” – and Cantrip, McDonald is part of the trio Bellwether, with English accordionist-pianist Alex Cumming and Orcadian fiddler Louise Bichan. His other collaborations have included Scottish/Cape Breton-style fiddler Katie McNally, Celtic trio Daymark, contra dance band Matching Orange, and stints with international artists like The Outside Track and famed Cape Breton fiddlers Andrea Beaton and Wendy MacIsaac. 

McDonald also has played with Americana-influenced sisters Ari and Mia Friedman (both of whom grew up in Newton), folk-pop band Pesky J. Nixon and Maine singer-songwriter Dave Rowe.

His Kalos colleagues are Tacoma, Wash.-based fiddler Ryan McKasson, a Scottish-style fiddler from California who has played with the likes of Alasdair Fraser and Hanneke Cassel and several bands, including a family ensemble with his sister, wife, and brother-in-law; and Vermont accordionist/pianist Jeremiah McLane, who explored several genres of music before immersing himself in Celtic and French traditions – he also co-founded the much-loved trio Nightingale, a force in New England folk music for a decade.   

Kalos describes itself as exploring the dark edges floating on the rims of tradition, including those of Scotland, Ireland, and New England. Their 2023 debut album, “Headland,” evokes what they term as “the dreamlike place between the land and the sea” – and in fact some tracks exhibit a phantasmagorical quality, as McLane’s piano accordion and McKasson’s fiddle swirl, churn, or glide through melodies that seem simultaneously native to several different origin points, supported by McDonald’s solid guitar rhythms and occasional flatpicking, or chiming mandolin.

On a medley of original reels, McLane’s “April and Joe,” with a New England vibe, unfolds gradually on accordion and mandolin, then hits its stride once McKasson joins in. McKasson leads into his mesmerizingly cadenced “Brownington Cèilidh Club,” McDonald matching him note for note on guitar until McLane re-enters, McDonald switches back to rhythm, and layered harmonies appear and shift as the tune continues.

 A joyous set comprising “Nia’s Jig/Luke’s New House/Roy Michael’s Reel,” all composed in honor of the band members’ children, offers a somewhat more conventional approach, and is highlighted by McDonald’s flatpicking in duet with McKasson on the middle tune and McLane’s piano accompaniment on “Nia’s” and “Luke’s” – he leads on accordion for “Roy Michael’s.”

Kalos dips into Scottish tradition with “Allen Water,” a gloriously emotive 17th-century air found in the storied Henry Playford collection: Each of the three takes a turn leading, their respective instruments’ characteristics (McKasson is on viola here) plumbing the tune’s shapes and contours, then take it home together. In an interview with TradFolk, the trio spoke of “Allen Water” as a hymn to the pastoral beauty of the Scottish landscape that – given the increasingly dire outlook for the planet – serves as “an ode to the peace found only in nature.”

Whatever dream state some of the instrumental sets may suggest, the songs – led by McDonald’s gentle but expressive voice, with bracing harmonies from McLane and McKasson – are very much grounded in realities, whether grim, wistful, or joyful. The traditional “Fare Thee Well” – also known as “Ten Thousand Miles” or “My Dearest Dear” – is a soulful lament of parting lovers, tinged by a steadfast, but likely vain hope of reunion. This particular version was first recorded by English singer/raconteur/song collector A.L. Lloyd, who in turn was the source for guitarist/vocalist Nic Jones’ gold-standard 1977 rendition. 

 More upbeat in tempo if not outlook, “The Brakeman’s Daughter,” written by criminally underappreciated Canadian singer-songwriter David Francey, is a reminiscence of unattainable love in a gritty setting, the relentlessness of the refrain (“Where the trains roll by/where the trains roll by”) underscoring the long odds against romance. By contrast, Alasdair Roberts’ “The Whole House Is Singing” is a charming, heartfelt homage to familial love and devotion (“We are stronger when the moon glows in the sky/And the moon causes the tide to rise and to rise”).

For McDonald, Kalos is the perfect vehicle for three people with a long history of involvement in, and respect for, folk and traditional music – but who also go beyond preconceptions about such music. 

“A lot of our repertoire is our own music,” he says. “You can definitely hear the influences from Irish, Scottish, Scandinavian, and Quebec traditions, which is why we call it ‘Celtic roots music.’ If we had to sum it up, I think we’d say that we like to play music that feels right to us, which is why we listen to a lot of music together, and we talk about what we hear in it.”

Growing up in a family where adults and kids alike played music, it might seem that McDonald was fated to follow suit – for a while he accompanied one of his sisters at local open mics – but he insists there was no pressure or expectation. He favored folk and acoustic music (“My mother liked Woody Guthrie, so that probably was an influence”), and found himself drawn to bluegrass, especially after hearing the band Crooked Still. Having picked up mandolin, McDonald branched out to Irish and Scottish music and also began playing for New England contra dances. 

What had been just good fun became, in McDonald’s words, “more of an endeavor” when he began studying at the Berklee College of Music, and learning from respected musicians like John McGann and Eugene Friesen. “It was very intensive,” he recalls. “You worked hard and sometimes you got your head handed to you. It definitely got me serious about playing music – and about picking up guitar – and I started touring out of Berklee.”

McDonald always relished the folk scene’s social aspect, such as the after-parties for concerts, festivals and other events, where new friendships are often forged and ideas for collaborations take root. One such occasion was the 2013 New Hampshire Highland Games and Festival at Loon Mountain was a major launch point for both his musical and personal life: Among the acquaintances McDonald made that year was his future wife, Sarah, and McKasson.

“There just happened to be a lot of people there that year who ended up being important to me,” he says. “Ryan and I really hit it off, and we decided to record an album. I’d met Jeremiah – who was a big inspiration for me – at the Maine Fiddle Camp, and as it turned out, Ryan already knew him and invited him to play on our album. So, technically, our collaboration started even before we became a band.”

Plans are afoot for recording a new Kalos album next year, to be produced by the estimable Yann Falquet, a renowned Quebecois musician who is a member of the trio Genticorum and often plays with McLane’s former fellow Nightingale friend Keith Murphy.

“We were very happy with the first experience, which was an important stage in our development as a band,” says McDonald. “We’re excited to be at this point in our life as a band, and look forward to moving ahead.” 

 For more about Kalos, see kalosband.com