Later this month, Jan Agee will leave her Davis home, get on a plane, and fly 6,000 miles to Germany just to attend an opera. And she isn’t even an opera fan.

But she is a fan of this one. “Grete Minde” is a three-act opera composed by her grandfather, Eugen Engel, a Berlin businessman and self-taught musician. He completed the opera in the early 1930s and for several years tried to get it staged, but with the rise of the Third Reich, there was no way for a Jewish composer in Germany to succeed. Or survive.

Engel was murdered in the Sobibor concentration camp in 1943. His handwritten magnum opus, preserved in a single bound volume, gathered dust inside a trunk for decades. But now, after a series of small miracles, “Grete Minde” will have its world premiere on Feb. 13 at an opera house in Magdeburg, Germany.

Agee, 74, and her brother, Claude Lowen, 84, of San Francisco, will be there to honor their grandfather, take in the music and absorb the profound meaning of the occasion. “To me it’s tremendously exciting and gratifying,” Lowen said. “And unexpected.”

Added his sister, “I’m surprised how successful this has been, that all the pieces fell in place, and that there are people in Germany who, when they heard the story, were touched by it and wanted to keep it alive.”

It’s a story Engel’s grandchildren pieced together over a period of years.

As a girl, Jan knew about the trunk in the basement. It was brought to San Francisco by her mother, Eva, Eugen’s only child, when she immigrated in 1941. The family belonged to Congregation Emanu-El, and Jan enjoyed a happy childhood, but she knew little of her grandfather’s German backstory. Eventually, she became curious.

“At some point, I opened the trunk and looked in,” she recalled. “I didn’t know there were a lot of other papers in there. It later became a mission of mine to figure out what we had.”

“We don’t know how he got into music,” her brother said of Engel. “He was a businessman in the textile industry. Whether he had music training, we never heard, but he had wide musical contacts in Berlin, so he was active in that world.”

In the trunk was a trove of musical scores, photos and correspondence between their late grandfather and notable 20th-century German music figures, including conductors Bruno Walter and Adolf Busch, and composer Engelbert Humperdinck. It turned out that Engel, who was born in 1875, was a prolific self-taught composer, having written numerous lieder (German art songs), choral works, chamber pieces and the opera “Grete Minde,” based on a popular 1880 novel by Theodor Fontane.

His music career, and everything else, fell apart in Hitler’s Germany. Engel’s daughter and grandson fled to Holland in 1935. He eventually joined the family in Amsterdam in 1939, and though his daughter, son-in-law and young grandson made it out of Europe, Engel stayed behind, trying to secure a visa to join them in America. All the while, he wrote long, loving letters to his family, all of which were preserved.

The Nazi occupiers of Holland eventually arrested and deported him, first to the Westerbork camp and then to Sobibor. In San Francisco, Eva carried on, though she rarely spoke of those awful days in Europe, her brother recalled.

Lowen and Agee did well. He became a successful San Francisco lawyer, while she worked in California state government, serving in the Department of Consumer Affairs and the Department of Education. She also worked in the nonprofit world and taught writing at community college in Sacramento.

A few years after their mother died in 2006, Agee, by then the mother of three grown children, got a call from an archivist at the Jewish Museum in Berlin who had read Eva’s obituary in J. “He wanted to know if I had any papers or artifacts to donate to the museum,” she recalled. In 2012, Agee traveled to Berlin to deliver some of her grandfather’s papers to the museum.

The next year, Engel’s music was finally heard. Agee had arranged to have some of his lieder performed by cantorial soloist Rebecca Plack of Sacramento’s Congregation Bet Chaverim at a concert held at a private home. Agee remembers seeing many attendees in tears.

But it didn’t stop there. That Berlin archivist, Aubrey Pomerance, had also been curious about the music scores, which had lain neglected for nearly 90 years. “Aubrey wanted the music,” Agee recalled, “but I thought there was no chance it would be performed.”

She was wrong. The first step to the opera stage was taken when Agee and Lowen arranged for the installation of a stolpersteine, or memorial stone, near Engel’s former Berlin home. These stones have been placed all over Europe as permanent reminders of the Shoah’s horrific toll.

For the 2019 installation, Agee had one overriding wish: “I wanted to see his music played at the ceremony,” she said. “I realized down the street [in Berlin] was a music school. I contacted them to see if they would be willing to have someone perform the lieder. They agreed right away.”

After artists from the Hans Eisler music school performed Engel’s songs at the ceremony, it started a chain reaction in German music circles. Ultimately it reached Ulrike Schröder, the dramaturg at Theater Magdeburg, who was very interested in examining the opera. Once the painstaking task of copying and digitizing the handwritten score for orchestra, soloists and chorus was completed, Schröder and her colleagues knew they had something special. Composed in the post-Wagnerian era, when Gustav Mahler and Richard Strauss held sway, Engel’s music truly held up.

“It’s in the late romantic opera style,” Schröder said, “and we realized it would be a good thing for a German opera house to do. The music is fine, the story is by a famous German writer, set in a city near Magdeburg, and the librettist is from Magdeburg. So we said, yeah, we can do this.”

“Grete Minde” tells the story of a young woman, deprived of her rightful inheritance by her half-brother and the town council, who takes revenge on her hometown by setting fire to it. The title character dies in the burning church tower. “You can hear in it the music he loved, and he put it into it,” Schröder said. “In the culture in Berlin in the 1920s, the people were loving music. [Engel] worked 10 years on it.”

To connect the original 19th-century novel with the mid-20th-century conditions of the opera’s composition (and composer’s fate), the setting and costumes on stage will more closely resemble the 1940s.

Schröder noted that at the first rehearsal, singers, musicians and crew members were astonished by the opera and its Holocaust backstory. “People said, oh, that’s amazing and so moving. We want to do this.”

For Schröder herself, working on the project has been “an honor.”

The world premiere was to take place last October, but Covid-19 restrictions postponed it until mid-February. Now, omicron or no omicron, the curtain will rise Feb. 13 on Eugen Engel’s lost masterwork.

“Opera, of all the classical forms, is the most unlikely to be performed,” noted Lowen. “You have an unknown composer whose opera will be performed, which takes a tremendous effort. It’s remarkable.”

Agee’s only regret is that her mother isn’t around to see the opera performed. But other than that, the revival of her grandfather’s music in the nation that killed him has been a profoundly moving experience.

“As the Jewish daughter of Holocaust refugees and the granddaughter of a Holocaust victim, I often found it difficult to understand how the unthinkable was allowed to happen or to forgive the place where it happened,” she said. “However, the people at the Theater Magdeburg, through their dedication, passion and commitment to this project, have shown me that wonderful people are trying to correct the horrors of the past.”