It's just after 8:00 p.m. on the final day of summer, and Seattle duo Kimberly Morrison and Jesse Lortz show up to the beach at Golden Gardens to catch the last glimpse of a dwindling sunset. The sun has already disappeared behind the mountains, and a thin strip of reddish pink sunlight is slowly fading above the horizon's jagged, jutting silhouettes. As the sky dims to a dark blue embellished with twinkling stars, a handful of campfires begin to glow big and bright along the beach. But Morrison and Lortz, collectively and respectively known as the Dutchess and the Duke, sit in the dark, on a large cluster of rocks, a couple hundred feet away from the nearest flames.

"I'd like to sit by that fire," Morrison halfheartedly suggests. "We should crash it."

Instead, the duo huddle against the light breeze, gaze at the stars, and wonder whether the late summer moon is waxing or waning. "It's waxing," says Lortz. "It's getting bigger."

The Dutchess and the Duke—and their sound—are in a waxing phase as well. For most of this year, they have juggled a hectic tour schedule, jumping between one-off festival gigs and opening slots for Fleet Foxes, the Vaselines, and Modest Mouse, while taking time to record their new sophomore album, Sunset/Sunrise, in Oakland. At home, they're just as busy—Morrison is pulling double duty playing bass for Unnatural Helpers (who just finished recording and mixing their forthcoming Hardly Art full-length); Lortz has been in school and is the proud new father of a baby boy. They look a little bit beat.

Morrison and Lortz are old friends who played in various bands and shared many stages before forming the Dutchess and the Duke just under two years ago. (They're not a couple and not married to each other, contrary to the popular belief of some lazy journalists.) They released some of the first songs they ever recorded as the "Reservoir Park" single on Lortz's Boom Boom Castle label in October of 2007; the recordings so impressed Sub Pop sister label Hardly Art that the label signed the band (they were one of its first signings) without ever having seen the band perform live. At the time, the duo still hadn't played beyond the basements where they recorded (their first show happened months later at the Wildrose).

Their Hardly Art debut, She's the Dutchess, He's the Duke, established the band's basic sound: lightly strummed dual acoustic guitars, warm vocal harmonies and sing-along melodies, catchy hand-clapping and simple tom-tom and tambourine backbeats. When another one of the band's singles, "Never Had a Chance," was released last year on Chicago indie label HoZac Records, label owner Todd Killings coined a term to describe the Dutchess and the Duke's sound that has stuck with them: "campfire punk."

"It's what people use to describe us," says Lortz. "Which I guess is better than something like 'the groovy retro folk-rock stylings of Leonard Cohen doing the Stones.' I like it. I think it's kind of endearing."

That sound really came to life during last December's heavy snows, when Seattle was paralyzed by frozen roads and slippery sidewalks, and the duo played a special acoustic set for a friend's birthday in the frigid bowels of a gutted former restaurant/­nightclub that lacked proper heat. Those who braved the weather and trekked down to a dimly lit room barely warmer than it was outside stuck it out by huddling close around the band, drinking, and singing along. After seeing the band play around town on numerous occasions in 2008, including their first sold-out show at the Tractor Tavern, it was exhilarating to catch them in such an intimate setting, with no need for amplifiers and microphones. There was no campfire to provide heat, but there was a warm communal spirit in the air, everyone singing together in harmony.

"Campfire songs are universal folk real-person songs," says Lortz. "The whole reason we wanted to start this band was so we could go to Europe and just carry two guitars—just show up to play. That's my favorite way to do the band, because it's just me and Kimberly, on the road, having our adventures."

As Morrison and Lortz sit on the rocks, two trains heading in opposite directions pass by in the dark blaring their horns, halting our conversation. The train whistles recall not only the band's adventurous spirit—as though the pair might just hop on and hit the road that night—but also the faint sounds of fire-truck sirens accidentally captured at the beginning of Sunset/Sunrise's title track. Lortz explains that the Creamery, a punk warehouse in Oakland where Sunset/Sunrise was recorded, was in a dangerous part of town, and he describes the huge space they recorded in as "a natural reverb tank," though not one impervious to picking up some outside ambience.

Sunset/Sunrise also picked up the fine-tuned ear of former Gris Gris leader Greg Ashley, a gifted and versatile musician, who produced the album and played various instruments on most of the tracks, alongside regular D&D percussionist Donnie Hilstad, friend/former Gris Gris bassist Oscar Michel (the namesake of Lortz's 4-month-old), and a Bay Area–based session string player named Carey Lamprecht. The additional players and the large, looming space in which the music was recorded give the album a richer, more symphonic quality that's as emotionally moving as it is a departure from the band's earlier, stripped-down sound.

"It's really funny," says Lortz. "When 'Hands' [the lead single off Sunset/Sunrise] came out, people were like, 'Oh, I like their older "campfire punk" stuff.'"

"Hands" is a profound album opener and a good indication of what's to come. Soft acoustic strums weave through faint organ notes over a throbbing floor tom, while Lortz and Morrison sing, "Sometimes, girl, I'm already gone/I've been ready for so long/in your heart there's a different man/and I just ain't that strong," before Ashley's electric fret-work blows over it all like a southerly wind. Morrison's voice takes front and center amid giant cymbal splashes and washes of delicate strings on "When You Leave My Arms," and the vulnerability and loss in her lyrics make it one of the most emotionally intense songs the band have ever recorded. "The River" closes the album on a slight up-note, as though the last 29 minutes was an autumnal darkness and now the sun was rising again.

Although conceived over just a few late nights in Lortz's garage and recorded over the course of a weeklong spring break, the results are brilliant—Sunset/Sunrise stands to be one of the best records put out by a Seattle band this year, hands down.

I had hoped to make it all the way to daybreak on that beach, but it's still a long ways off when the Dutchess and the Duke have to head back to their busy personal lives. The sun is long gone, the moon is waxing over us, and the campfires are still burning on the shore. The sunrise can wait.