Click here to watch a video of a Rangers show.

The toilets in the basement of New York City’s B. B. King nightclub are overflowing. It is not a modest spill. More like a boot-high flood of unmistakable sewage, determinedly running through the premises as if tardy for an appointment.

Inside the dressing room backstage, adjacent to the surge, Steve Martin is picking his banjo, wearing a crisp suit, a pocket square, and supple leather loafers.

“Perhaps we should close the door?” he suggests with trademark understatement.

Martin is in town to play an unbilled gig with the bluegrass band the Steep Canyon Rangers. The Rangers, a group of five men—Woody Platt (33), Graham Sharp (34), Charles Humphrey III (34), Mike Guggino (32), and Nicky Sanders (31)—have been performing together for a decade, most since college at UNC–Chapel Hill, where they evolved from a likable group of promising amateurs to one of the premier acoustic acts touring today.

Martin, who has played banjo for forty-five years, connected with the Rangers through “pure serendipity. I was at a party in North Carolina. The band came over, and they were great.”

Martin had just recorded his own bluegrass album, The Crow: New Songs for the Five-String Banjo, which would go on to win a Grammy in 2010, and he needed a touring band.

“I had played with the Rangers once onstage and it was sort of magic for me. The songs had never sounded that good.”

For their part, the Rangers were eager to learn a new catalogue of music, something they believed would strengthen their already formidable skill set. They were also fine with playing to a packed house every night, something Martin, with his fame, could guarantee. The match was made, and the men have collaborated seamlessly since. Well, almost.

“Initially it was difficult for me to fit in with a group of well-honed musicians,” Martin admits. “Onstage, when to come in, when to go out. I had to learn so much. They were tolerant.”

“Steve was nervous the first gig,” recalls Platt, who remembers his new bandmate suffering some pronounced queasiness. “It is still one of my favorite performances of all time.”

Tonight at B. B. King’s, the billing lists only the Rangers. Martin will be a surprise guest, sitting in for a few songs, much to the shock of the moderate midweek crowd.

“I didn’t even know he played banjo!” whispers one gobsmacked guest when Martin walks onstage.“I didn’t know he played so well,” adds another.

Martin is accustomed to the astonishment. His facility is not what one would expect of any picker, let alone one who stars in movies with Meryl Streep. He tempers some of the shock by mixing comedy into the set, either with clever banter or within the songs themselves, numbers like “Atheists Don’t Have No Songs,” an a cappella riff hilariously lamenting the dearth of spirituals for nonbelievers.

Some folks sing a Bach cantata
Lutherans get Christmas trees
Atheist songs add up to nada
But they do have Sundays free