When Colleen Bertsch takes the stage at Trinity Church Community Center at Third Street and Avenue A on July 3, it won't be her first Bismarck show. She made her local debut as a fourth-grader in the all-city orchestra concert at Bismarck Civic Center, among a sea of elementary school kids. Her return promises something completely different.

Bertsch, a Bismarck native, now bows her violin for the Minneapolis-based band Orkestar Bez Ime. OBI - Bulgarian for "orchestra without a name" - combines traditional music from all over the world but speciallizes in the Balkan region of eastern Europe. The mood of the music ranges from playful to sultry, sometimes within a single track, and sometimes manages both simultaneously. "Sestorka," track 12 on the group's newest album, "Lake Aquanyet Days," would be perfect for a bar mitzvah. But No. 5, "Rumelaj," is more like the soundtrack for a scandalous belly dance. It's hard to decide if it would feel natural to see your grandmother dancing at an OBI concert, or horrifying.

Bertsch grew up playing violin in the classic style. She earned her musical chops in the Bismarck public school music program, and with Strolling Strings and the Bismarck-Mandan Symphony Orchestra. Her new career in international music came about through serendipity and hard work. She went to the University of Minnesota music school to continue her study of classical violin. After graduation, she was invited to try out for the Ethnic Dance Theatre.

"One day I got a phone call,"she said. "Somebody knew somebody who knew somebody, and they needed a violin player. They said, 'The rehearsal is in two hours - can you come?'"

After some gentle deception about how easy it would be, she went, and she got the job. When Bertsch and four other members of Ethnic Dance Theatre decided they wanted to take their ethnic dance outside the theater, the orchestra without a name was born.

But the music from Romania, Israel and elsewhere was, well, foreign to Bertsch.

"This stuff was so different," she said. "They have all these unusual meters and a really odd counting system."

It was two years before she really grasped the intricacies of the music, she said. Since she found her new passion, she has traveled to the Czech Republic, Mexico, France, Hungary and Serbia in search and study of ethnic music. She spent some of those trips simply recording the music she heard in villages and city squares, but her last trip - to Budapest - was to study under a violinist of some renown. Bertsch is eager to bring what she has learned back to Bismarck.

"I've been wanting to do this since we got the group together," she said. "Eastern Europe is just a little bit on the exotic side. I am really excited to come back to Bismarck and share it."

She especially looks forward to sharing her passion with her family, who has yet to see her perform with OBI. "It's almost like I have a kid they've never met," she said.

Orkestar Bez Ime has something of a following in Minnesota. Every song they play has a dance to go with it, and many fans know them all, Bertsch said. Those who don't know the steps need not worry, though. The music is easy to enjoy without dancing, but the band promised to spend part of the show teaching the audience the moves.

"We say, 'If you can walk, you can do these dances,'"Bertsch said. "They're totally easy to learn. You can pick it up in about half a minute."

Even your grandmother.