Whitey Morgan and the 78s perform Tuesday night at Hill Country in D.C. (Josh Sisk/FOR THE WASHINGTON POST)

The Hill staffer happy hour ended an hour ago. The tour group of chatty French teenagers had wolfed their cupcakes, and their chaperon had signed the check. It was time for Whitey Morgan and the 78’s to get to work.

With beards out of the Bible and forearms cluttered with tattoos, the Michigan country singer and his four-piece band gave a stellar concert Tuesday night at Hill Country, the bustling Penn Quarter barbecue barn with a basement that transforms into a quasi-honky-tonk at the stroke of 8:30. With only a few dozen fans scattered across the downstairs dining room, it still might have been the best country show the Washington area will see all summer.

And summer is the season when Nashville’s biggest names link arms and hit the highways in clusters, playing to swollen crowds at leafy outdoor venues. So consider Tuesday’s gig an important reminder that there are still plenty of lonesome underdogs wandering the interstates, crooning for tiny audiences in cozy basements that reek of smoked brisket.

Playing two sets that each spanned about an hour, Morgan spent the night balancing his own fiery tunes with nods to the gods of outlaw country, namely Waylon Jennings. His rendition of “Waylon’s Still the King” — a song that updates the words Jennings sang on “Bob Wills is Still the King” — cleverly bowed before two generations of country icons. But the song’s parting shot was aimed at Morgan’s peers: “Pretty boy, you might be on CMT, but old Waylon’s still the king.”

That whiskey-filled water balloon was most likely lobbed in the direction of Jason Aldean, Brantley Gilbert and Justin Moore, three young, wildly successful mainstream country artists. They’ve each adopted a tough-guy image that can be traced back to the late-’70s outlaw country movement, but they rarely sing about the mountains of cash and cocaine that Jennings and Willie Nelson once scaled.

On Tuesday, Morgan and his band shrewdly illustrated that the legacy of outlaw country isn’t about the white lines. It’s about the bass lines.

The no-nonsense bricklaying of Ted Russell Kamp, who used to play bass for Jennings’s son Shooter, exuded an undeniable gravity. He and drummer Tony DeCillo consistently pushed these songs toward rock-and-roll, injecting cuts from Morgan’s self-titled 2010 album — “Buick City,” “Turn Up the Bottle” and “I Ain’t Drunk” — with a renewed confidence.

Morgan, meanwhile, sang Dale Watson, Merle Haggard and Johnny Paycheck tunes with a rowdy reverence that was just as pleasing. But his version of Bruce Springsteen’s “I’m On Fire” was a standout. Where most cover songs drag the original into the future, this one seemed to pull it into the past, swaddling the Boss’s melodies in steel guitar and sunburnt vocal harmonies.

Time continued to bend with a take on Jennings’s “Waymore’s Blues,” Morgan trading licks on his Telecaster with steel guitarist Brett Robinson. When the song ran its course, Morgan and harmonica player Daniel Robert Coburn reprised its opening lines in high harmony, as if the lyric sheet had twisted into a Mobius strip.

Let’s hope the road brings these guys back again soon, too.