Whatever else may happen, rest assured someone will play a banjo.

Lydia Ramsey, most likely, though she’ll also be picking guitar alongside Benjamin Doerr, frontman/founder and primary singer-songwriter of local indie-folk group St. Paul de Vence, during a special one-night-only concert at Rolling Bay Hall on Saturday, Feb. 29.

The show’s set list is mostly fixed, but some last-minute additions and subtractions are inevitable, according to Doerr. They might even take a request or two.

The banjo, though, that’s definitely going to happen.

“I think [she will play] guitar and banjo — and singing of course,” Doerr said. “But there will definitely be banjo, fear not.”

Accompanied by Alex Calejs on piano, the so-called “St. Paul de Vence Duo,” a kind of parred-down version of the group, are the latest act brought to Rolling Bay by WEAVE Presents, a Bainbridge-based nonprofit performing arts and education organization that hosts international musicians, showcases the local independent arts community, and “invites audiences to celebrate the multi-racial, multi-ethnic roots of American culture.”

Doors open at 7 and the show begins at 7:30 p.m.

Tickets, $20 in advance and $25 at the door ($10 each for youths age 3 to 18 in advance), are available now via www.weavepresents.org.

Doerr and Calejs live on Bainbridge, and Ramsey recently relocated back to Indianola after having lived on the other side of the Sound, which has allowed she and Doerr to play together more often.

“Lydia and I do a lot of work as a duo,” Doerr said.

“We don’t always promote it that way. Specifically, we felt it was important to promote it that way on Bainbridge because it’s home and people know the band and I didn’t want people to expect a full-band show. I don’t think people really care; if they get a good show, they’re happy, but I always feel like I want to be as transparent as possible about how the show’s going to go.”

That is, when he knows how it will go.

One of the reasons playing as a duo with Ramsey is so appealing to him, Doerr said, is the ease with which a smaller group can improvise.

“I love singing with her and performing with her in any setting,” he said. “But I think what we can do as a duo, or in a smaller combination, is that we can rehearse something one way a million times and then in the moment if we want to do it differently it’s a lot easier to sort of just move the two of us in a certain direction. Because if you have a rhythm section following you, you could be derailing something pretty quick if you’re jumping off the rails in a way you haven’t rehearsed it before.

“I think with Lydia, we have this room to kind of breathe and experiment in real time.”

The two first met about six years ago when Ramsey was working at the Triple Door in Seattle and St. Paul de Vence (an earlier lineup) played there. Soon after a personnel shakeup left the group light handed.

“I reached out to her and said, ‘Do you play banjo?’ and she said, ‘Sure,” Doerr recalled. “She was just learning, had just gotten a banjo, but she picked it up real quick and sat in on, I think, five shows that we had committed engagements for.”

Calejs, too, is a more prominent member of the group of late.

“He has been playing keys with us for a while now, I think over a year,” Doerr said. “With the full-band setup as well, he’s played with us at the parks shows and with our album release last year and a number of shows. He’s been a great addition to the lineup.

“We were going to do this thing as just a duo and then there’s a grand piano at the WEAVE space and it seemed silly not to use it,” he added. “We’re going to use him in a bunch of stuff, so it’ll be almost like a trio show.”

Having withstood comings and goings, relocations and a shifting Seattle music scene, St. Paul de Vence now boasts a history almost as storied as it’s namesake, a foreign locale adopted for decidedly personal reasons by Doerr.

“St. Paul de Vence is a town in the south of France … about 45 minutes outside of Nice, where my grandfather grew up,” he explained. “He grew up in Nice and he was coming of age in Nazi-occupied France and then when the Free French [Forces] landed and moved into Nice, he joined forces. He signed up to go on and fight with them throughout the remainder of the war and he was stationed in St. Paul de Vence … for his training and sort of his initiation into the Free French Army. And I went there with him right when I was starting to write his stories into these songs and I was like, ‘Well that works.’”