Songwriters have been using music to tell stories for centuries, but not quite the way Peter Miller does it.

The frontman for a Minneapolis indie rock band, Miller created an entire concept album based on letters his grandparents exchanged during World War II.

Miller and the rest of We Are the Willows will perform music from that album, "Picture (Portrait)," at 7:30 p.m. April 5 at the Sheldon Theatre.

The group will be in Red Wing all that week, conducting free workshops for students, seniors and community residents.

Miller is the original We Are the Willows - a curious name for a solo act, he admits. "Willows are some of the strongest trees, with deep roots," he explained. "We're stronger together. We Are the Willows is a statement of that."

"I've always been interested in family," he said. "I find strength in family" - using that word in the broadest sense. Miller considers close friends and people in his life that he is "tethered to" as family.

After touring extensively, Miller realized he missed the collaborative process of playing with others, so he built a band about seven years ago.

The concept of "People (Portrait)" had been developing long before that.

Miller lived with his grandparents in the Twin Cities area while attending college. That's when he learned about the letters his grandfather had written to his grandmother while he was stationed overseas.

His grandfather had proposed to her in 1942, but she wasn't ready, Miller said. Instead, a courtship ensued through letters. His grandfather wasn't able to keep the ones she sent him while he was stationed in the Southwest Pacific, but she kept his.

They continued writing when he returned stateside - he kept the letters she wrote during that time - and ultimately reconnected.

"I tried to understand what that would have felt like," Miller said. "Even after reading the letters, there's a lot of stuff you really can't understand unless you've been through that experience or something like it."

His grandmother gave him the letters when he graduated. Miller had asked for them, because "I wanted to sense who they were as young people."

At first he did not realize they would become songs. "I just couldn't help myself," Miller said.

Those songs, which are at the heart of "People (Portrait)," explore themes of family, separation, life, death and identity in a time of national and personal crisis, according to his Website. Reviewers say "The songs communicate complex ideas delivered with pop-sensible charm."

In Miller's view, "With all the new technology and social media, I feel that people are able to tell stories in all sorts of ways." His way may look a bit different, but it boils down to being a songwriter and a storyteller.

On stage, a We Are the Willows performance is a mix of singing/playing and talking about the letters and what his grandparents' experiences meant to him. The audiences also will see images of the people who inspired the show.

The other members of the band were an integral part of developing the performance, said Miller. He wrote most of the melodies and words, but when the process shifted to performing them, they added dynamics and articulation.

Miller, who also is a countertenor and guitarist, is joined on stage by Jeremiah Satterthwaite on guitar and banjo; Leah Ottman on violin, keys and vocals; Hilary James on cello, keys and vocals; Travis Collins on bass; and Stephen Lindquist on drums and vocals.

According to the Sheldon, they create "dynamic, intimate songs with instruments and voices combining to create energetic rhythms and intricate melodies. Their heartfelt arrangements evoke shared nostalgic feelings of love and loss."

But it's not only nostalgia, according to MPR reviewer Andrea Swensson. "In the hands of We Are the Willows," she said, "it becomes a story not just about his grandparents, but about anyone who has ever been pushed down into the darkness and pulled out again."

The album, which was released in 2014, led the Minnesota State Arts Board to award them a grant supporting their current Minnesota tour. The performers, who all play with other groups and maintain side jobs, have been in residence in Northfield and Winona. They look forward to their Red Wing visit.

He's played in Red Wing before, Miller said - performing at the Big Turn Music Festival the last two years. This year he and Hilary James performed at Christ Episcopal Church.

The "Picture (Portrait)" concert will be at 7:30 p.m. April 5 at the Sheldon. Tickets are $15. For information or reservations call 651-388-8700 or go online to www.sheldontheatre.org. The site includes links to their music.