For its one-of-a-kind sound the Burnett Sisters Band, after 13 years' preparation on the relevant circuits, is ready to be a harbinger of the bright future of bluegrass. Easy Come, Easy Go is hardly your ordinary release in the genre. If you should happen to hear it yet fail to notice it, you might have your ears checked alongside your capacity to recognize music that warrants rather better than a casual shrug.

No, it's not within the standard definition of modern bluegrass, which emerged in the late 1950s, just a few years after the genre name "bluegrass" came to be. It continues to the present, in some manifestations bearing only a modest resemblance to what Bill Monroe had in mind when he fashioned the genre from a synthesis of old Appalachian music and the mid-'50s Grand Ole Opry.

The BSB, only loosely championing any one spot on the bluegrass spectrum, is composed of three siblings, Anissa, Sophia, and Anneli, as well as one unrelated male, English guitar/banjo player/songwriter Geary Allen. This outfit is not performing in what sounds like a language foreign to bluegrass -- not at all; it's just that it's a bluegrass language you may not have heard before. While eclectic, it still feels comfortably organic, never as if forced into existence. If not conventionally traditional either, it is not wildly distant from that approach. A close listening will tell you why: nearly all of bluegrass is here, along with other touches one rarely encounters at least in this form and in this context.

It is pretty certain that you couldn't pull off something like this if you don't know a whole lot about bluegrass and its history, more in fact than many working professionals are able to claim. Each of the band members has some variety of association with the Bluegrass, Old-Time, and Roots Program at East Tennessee State University, in other words an approach learned from more than the Burnetts could have picked up entirely from their native Boone, North Carolina, (home, too, of the late, legendary Doc Watson), or even from the area fiddle festivals on whose stages they play regularly. Their knowledge from formal study enables the four to grow the bluegrass vocabulary in a way that can render it at once novel and familiar, never missing the right notes, literally or otherwise.

The tracks, seven of them originals, evoke pleasure -- with one exception to be noted -- in a fashion unique in the genre. (I haven't listened to every bluegrass album, of course, but I've consumed a fair number of them after a lifetime's obsession to know something about what's on them.) Yes, there are "melodic" bluegrass songs and tunes, but that is not an adjective one finds often at the top of the list as a listener reflects on the genre's attractions, which more often derive from rhythm, harmony singing and story.

That's why there's the phrase "bluegrass state of mind." It doesn't apply even to the genre from which it derived, oldtime mountain music, dotted as it is with conventionally tuneful folk and popular airs, whereas bluegrass, no doubt owing to its banjo base, often enough conjures up images of nothing so much as flight from captivity. But Easy Come is crowded with the sorts of smooth melodies long integrated into vernacular material. Played as expertly as one could ever want, I might add.

Besides bluegrass in more standard form (e.g., Allen's "Fool's Gold" and "Sorrow, Grief and Pain"), the album draws notably on folk (both authentic and revival) influences. One example is Allen's "Don't Let Me Fall," as if an answer to the much older mountain growl "Let Me Fall"; though not in mood, the latter expresses what everybody who knows it would agree is a drunk and pissed-off state of mind. Allen's is a sad, sweet number about a failed relationship, as is his Carter Family-like "Whispering Wind," a heart song with hair-raising harmonies echoing a distant era when people talked that way. (Incidentally, the BSB's harmonies are not quite what one would anticipate in bluegrass, but they turn out to be more than welcome just where they are. You will not soon forget them.) Allen also wrote, unusually, "The Youthful Soldier," apparently set (so I infer) in the American Civil War, among the most noteworthy in this collection of already top-drawer material. A medley of fiddle tunes reminds us why there is a rich and surviving Southern tradition of such things.

To my taste the quality buckles only on "Lovesick Blues," performed decently enough but sufficiently cliched (down to its steel guitar) to be long overdue for retirement. It was Hank Williams's first hit but somebody else's idea. He learned it from a recording by blackface-minstrel performer Emmett Miller, who got it from a composition by Irving Mills and Cliff Friend. While as a songwriter on his own Hank was an undisputed master, "Lovesick," no masterpiece of any kind, owes its fame to his vocal pyrotechnics alone. Without them, it's just another vacuous pop ditty with which even the BSB can't do much. My sole complaint, I promise.

Otherwise Easy Come and the band that carries it are something special, among the most interesting and appealing interpreters I have heard in a while of a kind of music from which, however much one may love it, one usually does not expect surprise. If not prepared for this, I'm happy to celebrate it as among the highlights of my listening life -- which was a good one -- over the past year.