A little-known Holocaust hero saved thousands, including a boy who became a University of Utah professor. Hundreds of Utah teen musicians will tell the story.

Daniel Mattis was 7 when his family narrowly escaped the Holocaust, leaving on the last train out of Brussels, Belgium, before Nazis bombed the tracks behind them.

The family made it to Bordeaux, France, where they were among tens of thousands of Jews and other refugees who got visas signed by Portuguese consul Aristides de Sousa Mendes — in defiance of a dictator’s order — in June 1940.

Mattis, now a University of Utah emeritus professor of physics, will be in the audience Saturday when the Utah Youth Orchestras and Ensembles present Neely Bruce’s “Circular 14: The Apotheosis of Aristides,” an oratorio dramatizing Sousa Mendes’ act of conscience.