An Avett Brothers musical is testing the waters. Next stop: Broadway?

It was the start of a process of sorting the music, composing a script and combing historical records for a dark tale that, six years later, would unspool in Arena Stage’s Kreeger Theater. “Swept Away,” the story of four men, adrift after their boat sinks in the Atlantic and compelled by extreme privation to conspire in a horrific act, starts a crucial engagement Saturday in a run that may determine whether it survives to run another day, on Broadway.

Despite a director with a major résumé (Michael Mayer of “Spring Awakening” and “Funny Girl”); a cast including Broadway veterans John Gallagher Jr. and Stark Sands, and a skilled book writer in Logan, a Times Square mooring is nowhere near settled. Based on real events and inspired by a 2004 album, “Mignonette” by the Avett Brothers, a band led by Seth and Scott Avett, the 90-minute musical is compact and intense, certainly not the kind of fare that calls for jazz hands or tap shoes.

“It’s a tricky piece,” Mayer said, sitting in an Arena rehearsal room. “I don’t know that there’s a template that this can fit into.”

That, of course, may be a good thing. Musical theater too often relies on tried-and-true formulas, reinforcing a creative stasis in the form. While “Swept Away” broadly belongs in the category of jukebox musical, its folk-rock songbook by no means qualifies as the sort of branded pop that has driven past hits such as “Jersey Boys,” “Tina: the Tina Turner Musical” and “Beautiful: The Carole King Musical.” Which are all celebrity biographies, polished off with familiar music.

“Swept Away” is a musical with higher aspirations. Logan pored over hundreds of the Avetts’ songs to settle on the 16 that would complete his narrative. As it turned out, only three songs made it into the musical from “Mignonette,” the album the Avetts composed about the 1884 sinking of the yacht by that name, which went down during a voyage from England to Australia. Lost at sea for more than two weeks in a dinghy, the crewmen resorted to cannibalism to survive: Three of the crewmen were eventually rescued, and were subsequently charged with killing the fourth.

For Logan, the Avetts’ music proved a stirring emotional and expositional framework for this strange and disturbing tale. The more he listened to a range of other Avett songs, the more the catalogue spoke to him about how to tell it.

“The song “Murder in the City,” it’s a beautiful song,” Logan said, referring to a track for two guitars from the Avetts’ 2008 album “The Second Gleam.” “I thought, ‘Oh, this is a song between two brothers.’ So I made two of the characters brothers entirely based on that.”

Landing “Swept Away” reflects Arena’s ambition to be a developmental hub for musical-theater producers with Broadway in their sights. The Tony-winning smash hit “Dear Evan Hansen” was birthed at Arena in 2015, several years after “Next to Normal” found its footing on the company’s stages, and then went to Broadway, where it won the Pulitzer Prize for drama. More recently, the political musical comedy “Dave” (2018) and the bio-musical “American Prophet” (2022) used Arena as a testing ground.

The process was all totally new to Seth and Scott Avett, who live outside of Charlotte, when they were approached in 2014 by Matthew Masten, a budding theater producer. He found their longtime manager, Dolphus Ramseur, on Facebook. “What do you think about an Avett Brothers musical?” Masten emailed Ramseur.

“You send one of those emails and half the time no one responds,” Masten said in a Zoom interview with producing partners Sean Hudock and Jamie Forshaw, the latter from London’s Madison Wells Live company. (The partnership is underwriting some of the Arena production’s costs.)

“The other half,” Masten continued, “they say no, outright. But Dolphus responded almost immediately. He said, ‘This sounds like an amazing idea.’”

The Avetts, too, were all for it — and really not that surprised by the proposal. “I think when we’re making something from our, you know, from our heart, you can see it being anything you believe that it can be,” Scott Avett said in a joint Zoom with Seth. “It didn’t seem so out of left field, especially considering it was partially inspired by a record that we made. And it had already put in our minds the legend and the great drama of that story. So to imagine it being retold in this dramatic way does line up pretty well.”

It so happened that one of the actors recruited for the project, John Gallagher Jr. — who won a Tony playing the troubled student Moritz in the original 2006 Broadway production of “Spring Awakening” — was already a rabid Avett Brothers fan.

“This is how full circle this is for me,” Gallagher said, in a joint interview backstage with the actors playing the other three pivotal crew members: Stark Sands, Wayne Duvall and Adrian Blake Enscoe. “When I was doing ‘Spring Awakening’ with Michael Mayer on Broadway, I was such a die-hard Avett Brothers fan, I had a T-shirt I bought off their website. And anybody that came to the stage door — we had a lot of young kids coming to the stage door — I was wearing the shirt and I would tell them, ‘You gotta listen to this band. They’re so cool.’”

The actors have already been through a lot with “Swept Away.” They appeared together in the show’s premiere production, under Mayer’s direction, in 2022 at the Bay Area’s Berkeley Rep, a run that occurred just as the omicron coronavirus variant took hold and wreaked havoc with the cast, staff and box office. The show sometimes played to houses only 30 percent full.

The other day, as the “tech” portion of the rehearsal period was underway, set designer Rachel Hauck and costume designer Susan Hilferty stood at the back of the Kreeger’s orchestra seats, observing as the deck of a massive a wooden ship was being installed. Much of the hardware of the Berkeley Rep version has been transported to Arena. But at Mayer’s urging, the human scale of the show has been expanded, with additional actors recruited to play ancillary crew members. The notion was to give the show’s opening scenes more heft, and after the shipwreck, to heighten the impression of the surviving quartet’s isolation.

What happens between now and the end of the year is an attempt to see how successfully the “Swept Away” concept floats. It also happens that the Avett Brothers will only now get their first live taste of how their songbook has been treated; the pandemic prevented them from attending the show in California.

“We’ll see it several times,” Seth Avett said. “Because it’s a once-in-a-lifetime thing and, for me, seeing it is so surreal. And I fully believe that it’s a blessing to this existence that we all live in, in the creative world.

Swept Away, music and lyrics by the Avett Brothers, book by John Logan. Directed by Michael Mayer. Choreography, David Neumann; music supervision, Brian Usifer; arrangements and orchestrations, Usifer and Chris Miller. Through Dec. 30 at Arena Stage, 1101 Sixth St. SW. arenastage.org.