With a sexy beat, Rilo Kiley tests the indie limits

There is a girl in a tank top who appears in the lyrics of "Smoke Detector," a backbeat-powered, beach party-worthy romp on "Under the Blacklight," the fourth album by the much-loved Los Angeles band Rilo Kiley. She is not wearing a bra, and she cries "Danger!" when she hits the dance floor. Jenny Lewis created this character. But she can't completely relate.

"It's not me. I always wear a bra," said Lewis, the band's singer and principal songwriter.

"That girl without a bra is a real person," Jason Boesel, Rilo Kiley's drummer, quickly chimed in. "We saw her dancing at a Paul Frank party on the grounds of Wild Rivers, the water park. She didn't seem cool. But at that moment, she was hot."

Sitting in the parking lot of the Swinghouse studios in central Hollywood, chatting before a rehearsal for their upcoming European tour, the members of Rilo Kiley already seems a bit conversationally frayed. They're dictionary-definition critics' darlings: four smart, stylish musical adepts whose elegant pop has a vintage sheen and the most thoughtful lyrics this side of a Stephen Sondheim musical. "Under the Blacklight," which will be released Tuesday, already has earned raves in the big glossy music magazines and is No. 2 (behind M.I.A.'s "Kala") on the charts at the leading indie Web retailer Insound.

Still, this music takes a bit of explaining, since it veers from the bookish bohemian vibe that helped Rilo Kiley become the darlings they are.

"It has a different tone in a lot of ways," said Lewis. "I don't know if it lacks the feeling from our previous records, but it was an attempt on my part to create something different. The sound on this record is as important as the lyrics, if not more important."

Rilo Kiley won the fussy hearts of indie rock eggheads with three albums' worth of extremely pleasant and progressively more polished folk-pop. Often standing just outside the stories she wove -- "It wasn't me, I wasn't there, I was just watching from over here," reads a particularly telling lyric from her 2006 solo album, "Rabbit Fur Coat" -- Lewis dissected the romantic foibles of chronic overthinkers. Her voice was like orange sherbet: cool, sweet, a bit old-fashioned. The music was intellectually driven too, an amalgam of vintage moves and clever little gestures.