Town Mountain, out of Asheville, N.C., sometimes sounds like a cross between Flatt & Scruggs and the Steep Canyon Rangers. The former may have been the first band to "modernize" bluegrass when it was only newly invented in the early 1950s, and the Steep Canyon Rangers (in or out of Steve Martin's company) are doing it in the 21st century. Neither Town Mountain nor the Rangers, however, appear determined to reinvent the genre. The tradition is happily resplendent in both, especially so in the former. And yet....

Leave the Bottle, in fact, affirms the vitality of a genre that, in the right hands (and these are the right hands), has the capacity to effect change by staying as if the same. The innovations Town Mountain, which consists of five young men, brings to bluegrass are so seamlessly integrated into the sound that it takes attentive listening to discern the astonishing subtlety of concept and practice. Bottle is plausibly heard as something at once like a classic mid-century Flatt & Scruggs LP and yet like a document of the 21st century's second decade. The vintage and the modern rub shoulders like natural companions, chatting easily.

Nothing feels forced at Town Mountain. The picking is sweet and un-rushed, the singing laid back in the Lester Flatt way (all members but fiddler Bobby Britt are also singers). The harmonies are old-school soulful, the songs (composed mostly within the band) uniformly strong, whether witty or woeful. Town Mountaineers carry their influences so casually that I'd heard "Up the Ladder" (by guitarist Robert Greer) three or four times before it hit me: this is what Chuck Berry would have written if he'd been a bluegrass picker. The wry sentiments get to what Berry was complaining about in "Too Much Monkey Business" -- which it bears noting also inspired the likes of Bob Dylan's "Subterranean Homesick Blues."

Mandolinist Phil Barker's "Greenbud on the Flower" brings to mind, perhaps, the songwriting of Norman Blake. Hardly anybody writes as well as Blake does, so that's a compliment. "Lawdog" doesn't hide its debt to the late Jimmy Martin; in fact, it's a cheerful tribute, and the singer could pass for, even be, Martin himself. Other bluegrass streams flow into Town Mountain's deep river: honkytonk, gospel, a new fiddle tune that feels older than its years, a murder ballad. In other words, bluegrass' component parts, then, now and (one hopes) forever. It's enough to restore your faith in music.