The 90-year-old pianist will make his orchestral debut with renowned cellist Yo-Yo Ma on Tuesday night at Boston's Symphony Hall. And they'll be playing music composed 70 years ago at the Nazi prison camp where Horner was incarcerated.
"It's an extraordinary link to the past," said concert organizer Mark Ludwig.
The performance will benefit the Terezin Music Foundation, an organization dedicated to preserving the work of artists and musicians killed in the Holocaust.
Led by Ludwig, the foundation is named for the town of Terezin, site of an unusual Jewish ghetto in what was then German-occupied Czechoslovakia. There, even amid death and hard labor, Nazi soldiers allowed prisoners to stage artistic performances.
Horner played piano and accordion in the Terezin cabarets, including tunes written by fellow inmate Karel Svenk. On Tuesday, Horner will play two of Svenk's works solo – a march and a lullaby – and then team up with Ma for a third piece called "How Come the Black Man Sits in the Back of the Bus?"
Svenk did not survive the genocide. But his musical legacy has, due in part to a chance meeting of Ludwig, a scholar of Terezin composers, and Horner, who never forgot the songs that were written and played in captivity.
Still, Ludwig found it hard to ask Horner to perform pieces laden with such difficult memories.
"To ask somebody who ... played this in the camps, that's asking a lot," said Ludwig.
Yet Horner, now a retired doctor living near Philadelphia, readily agreed to what he described as a "noble" mission. It didn't hurt that he would be sharing the stage with Ma — even if he thought Ludwig was joking at first.
"I told him, 'Do you want me to swallow that one?'" Horner recalled with a laugh. "I couldn't believe it, because it's a fantastic thing for me."
The program features additional performances by Ma and the Hawthorne String Quartet. In a statement, Ma said he's glad the foundation is "giving voice through music to those whose voices have been tragically silenced."
Horner was 21 when he was freed by Allied soldiers in 1945 after serving time at Terezin, Auschwitz and Buchenwald. His parents and sister perished in the camps.
And though his back still bears the scars of a Nazi beating, he remains spry and seems much younger than his 90 years.
When Horner found out about the duet with Ma, Ludwig said, "he was so excited, to me he sounded like a teenager."