Singer and guitar ace Chris Smither often gets approached by strangers with a question.

What’s the deal with him and best-selling mystery novelist Linda Barnes?

“They ask, ‘Do you know you are mentioned in every one of her Carlotta Carlyle books?’ ” Smither said by phone last week from the airport in Los Angeles.

Yes, he knows. Smither is Barnes’ human rabbit’s foot.

Barnes has been a fan of Smither for 40 years. She used to see him play at the former Sword & the Stone coffeehouse on Charles Street when she was a college student.

In 1987, Barnes published “A Trouble of Fools,” the first of her books narrated by redheaded, 6-foot-1-inch Boston cabbie and private eye Carlotta Carlyle. It was Barnes’ fifth mystery, but her first critically acclaimed bestseller. It mentioned Smither briefly.

“I thought, ‘Maybe Chris is my good-luck charm,” Barnes said by phone from her home outside of Boston. “I’m going to mention him again.”

Barnes’ 12th Carlotta book, “Lie Down With The Devil,” came out in paperback this year. Smither, of course, gets a nod.

“Usually it’s a mention, a sentence. Occasionally (it’s) a bit more than that,” said Smither, who has his own recent release, the soulful album “Time Stands Still.” He celebrates Friday with a show at the Regent Theatre in his hometown of Arlington. He’ll be backed by a band, the Motivators; his Signature Sounds labelmate Caroline Herring is also on the bill.

“I’m just part of the landscape in and around Boston,” Smither said of his appearances in the books. “Carlotta will be driving her cab, and hears me on (radio station) WUMB-FM. Or my name is on Johnny D’s marquee.”

The musician has reaped a few rewards from his literary fame.

“It’s strange,” Smither said. “There are some people who don’t have any notion about what my genres of folk or blues are about. But they know my name from Linda’s books, so they (come) see me play.”

Smither is clearly tickled that his old pal has made him part of her literary terrain. But Barnes - “a pretty mean slide guitarist herself,” according to Smither, says she owes him even more.

“My husband Richard and I met in Boston in the late ’60s,” she said. “He was an MIT student and he was seriously considering becoming a singer-guitarist. He auditioned at the Sword & The Stone one night and happened to hear Chris play. One set from Chris and he suddenly changed course. He thought, ‘I’ll never be this good. I better stay in school.’ So, I owe Chris a lot. Instead of a broke musician, my husband became a systems analyst.”

Barnes still loves Smither’s rhythmic, rootsy playing and the intelligence of his songwriting.