For their third album, Nickel Creek [ tickets ] finally shed their youthful innocence, delivering a complex and decidedly adult collection of progressive bluegrass and folk. "Why Should the Fire Die?" focuses on lovers and their plight: how much to give--how much to give up?

By now, Chris Thile and Sara and Sean Watkins have mastered the mandolin, banjo, guitar and fiddle--the album's instrumentals, "Scotch and Chocolate" chief among them, offer plenty proof of that.

But this is really a relationship album, as potent as any in recent memory. "Somebody More Like Me" tackles the downfall of love with candor and venom. "I hope you meet someone your height so you can see eye to eye / With someone as small as you," spews Sean Watkins. The song titles tell the story: "Can't Complain," "Best of Luck," and "Doubting Thomas" to name a few. Even the choice of cover, Dylan's "Tomorrow is a Long Time," confirms the trio's maturity.

A thoroughly pleasing disc, "Why Should the Fire Die?" captures Nickel Creek at a time of growth, their mesmerizing harmonies and prodigious playing now fueling some great music.