“It’s kind of crazy stepping into that lead role. I’ve been a side woman my whole life,” says fiddle player Jenee Fleenor.

Since moving to Nashville in 2001, she has toured with artists including Blake Shelton, Steven Tyler and Martina McBride, in addition to playing on hits such as Cody Johnson’s “’Til You Can’t.” But now, with her bluegrass group Wood Box Heroes, she is stepping into the spotlight and showcasing her talents as songwriter and soulful vocalist.

“I’ve always wanted to sing, but it’s been on the back burner,” Fleenor tells Billboard. “Fiddle wasn’t hot on the radio at that time, so I started songwriting and realized I could say things I wanted to say. It’s nice to have a fiddle playing, songwriting and vocal trifecta all in one place.”

It wasn’t long ago that Fleenor was touring with Shelton when vocalist/guitarist Josh Martin hired her — along with 15-time Grammy winner and bassist Barry Bales and banjoist Matt Menefee — to be part of a backing group for his run of acoustic shows. At the end of the 10-day gig, they had honed their sound and realized they each had more to give.

“Those shows locked the band in and solidified the sound and we thought, ‘We could probably make a record,’” says Fleenor, who adds she had songs stored away that she felt would be a great fit for the newly-formed group. “It’s always been a dream of mine to have a band of session-quality musicians. We hardly rehearsed. We played through the songs one time and got onstage.” Wood Box Heroes released its self-titled EP last year and now (Friday, June 7), its debut full-length, 444, has arrived.

The group’s quirky name came about thanks to a random Buc-ee’s gas station stop, when Fleenor saw two small Marvel Comics figurines, Thor and Groot, sitting atop the gas station pump. “We were looking for a name for a band,” Fleenor recalls. “I sent Josh a picture of them and he said, ‘Those look like some wood box heroes,’ and I thought that was a great name for a band. We went through probably a thousand more names, but came back to that.”

Once in the studio, the recording process came naturally and swiftly, given the years they have all spent in recording studios, laying down tracks for other artists and as part of other groups. As a result, Fleenor says 444 was recorded in just two days. “We wrote charts and mapped out arrangements so when we are in the studio we aren’t wasting time,” she recalls. “A lot of my vocals, I cut while we were tracking.”

Fleenor notes the group’s sound has been compared to bands ranging from Fleetwood Mac to New Grass Revival — and their expansive influences prove why. While Fleenor began playing Suzuki violin at age three, she was also raised on Bob Wills records (“’Faded Love’ changed my life,” she says), as well as Merle Haggard, George Strait and Willie Nelson. She also soaked in Cajun music, as her mother is from Louisiana. Meanwhile, Martin grew up on the bluegrass-influenced Eastern Kentucky sounds of Patty Loveless, Loretta Lynn and The Judds. And Menefee’s influences add an unexpected element to their sound, drawing on jazz, rap, pop and video game music. (Menefee won the Winfield Banjo Contest at age 17 and has since worked with artists including Bruce Hornsby, Jerry Douglas and Mumford & Sons; Bales, who alongside his work for Alison Krauss & Union Station, has played on albums for Willie Nelson, Kenny Chesney, The Civil Wars and Chris Stapleton, the latter of whom he won an Academy of Country Music Award with for song of the year as co-writer on “Nobody to Blame.”)

On 444, each member not only plays but also helped with songwriting: Fleenor co-wrote six tracks; Martin is the sole writer on a trio of compositions, “Cross the Line,” “Piece of the Peace,” and “Better When We’re Livin’”; and another of Bales’ Stapleton co-writes made it on the album with “Cannonball.”

“When we cut that, I had a flashback to the 1997 Alison Krauss & Union Station album So Long So Wrong,” Fleenor recalls. “That album influenced us all so much, so it was cool to find that intersection. I say Barry [Bales] is the hero of the Wood Box Heroes. I wanted to do a string thing on the front of that song as soon as I heard it, because it sounds like it should be in a movie.”

Elsewhere, “This Train,” which features Fleenor on lead vocals, joins the lengthy canon of train songs alongside Blue Highway’s “Endless Train” and Flatt & Scruggs’ “Petticoat Junction.” As Fleenor sats, “Once we got the ball rolling and figuring out the songs, I told Josh, ‘We need an up-tempo song — and every bluegrass band needs a train song.’ I was driving to a session and threw some melodies down in my voice memos. I was writing with Josh and Jim [“Moose” Brown] and this came out. It’s fun to sing and it showcases our musicality.”

Ahead, Fleenor, Bales, Martin and Menefee are slotting in Wood Box Heroes shows between their continued work playing with other artists and groups. For Fleenor, that has meant playing recent shows with “King George” Strait.

“As a fiddle player, I have to pinch myself. I’m playing ‘Amarillo by Morning,’” she says. “But getting to step into the artist thing was something I thought, ‘I don’t know if I’ll ever get to do that.’ I took a leap into this thing. I’m living my dream.”

And even though she is marking milestones off her list, Fleenor does have one bucket list item left: “My mom’s dream for me as a kid was to play violin at Carnegie Hall. I’m not playing classical, but maybe one day we can play some bluegrass there.”