"We're going to go down a tunnel," Rosanne Cash told the sold-out Birchmere crowd Saturday night, "but I promise I'll lead you out at the end." In the ensuing set, the Nashville singer-songwriter avoided most of her country-radio hits in favor of the darker, more personal material from her past three albums. She reinforced the starkness of the material by presenting it with a stripped-down trio: herself on acoustic guitar, Steuart Smith on electric guitar and Jim Hanson on hollow-body electric bass. As Cash probed the tensions and false facades of modern marriage, the show did resemble an amusement-park tunnel ride: shadowy, creepy and ultimately exhilarating.

Cash performs live so infrequently that she remains unpolished onstage -- making small flubs with vocals and guitar chords -- but her very rawness reinforces the songs, which abstain from the usual glib comments about relationships to get at the awkward admissions that come only in brief moments of honesty. When she sang "On the Surface," about the contradictions between a couple's social graces and private conflicts, her weary sighs captured the reluctance of such a confession. When she sang the feminist plea, "The Real Me," she sang with a determination so solid that it didn't need to call attention to itself.

Cash unveiled several surprises. Her ex-drummer Vince Santoro (who, like Smith and Hanson, comes from the D.C. area) made two guest appearances with bongos under one arm. Cash sang "It Came Upon a Midnight Clear" from the new "Acoustic Christmas" album; she sang "Road Widow," a sassy, unrecorded blues she wrote with Smith; and she sang a brand-new song, "Soon We Will Be Sleeping in Paris," an uplifting love song that pulled the show out of the tunnel just as she had promised.