On their own, Rilo Kiley's Jenny Lewis and Blake Sennett lack a little something. Lewis could have used the guitarist's melodic smarts on last year's solo album, Rabbit Fur Coat. Meanwhile, Sennett's other band, the Elected, really needs a singer. But together, they'll try anything once, making some of the new millennium's stickiest music a sultry mix of pop from the '60s, '70s and '80s. Rilo Kiley's fourth CD, Under the Blacklight, splits the difference between eras and between the Los Angeles band's songwriters. It's pretty much a tribute to 1970s LA in all its shag-carpet glory. "Breakin' Up" sets the theme: Blacklight is essentially an album about a relationship falling apart. (Little surprise that songs like "Silver Lining" recall Fleetwood Mac's 1977 breakup masterpiece Rumours.) "Breakin' Up" also serves as the record's centerpiece a full-on disco stomp that finds Lewis cooing, "It feels good to be free" over swirling strings, dance-floor percussion and a monster beat. Her liberation is liberating to hear. Rilo Kiley has never sounded so loose and limber. Check out the funky "The Moneymaker" and the seductive "Smoke Detector," in which Lewis and crew attempt to start their own dance craze.