When she visits St. Louis this weekend to see the life and death of her only child transformed into an opera, Su Zhen Chen will be seated near an aisle, and an exit.

“If I can endure, I will watch the whole opera,” Mrs. Chen said in a phone interview this week before leaving her home in New York. “If I don’t feel like I can bear it, I’ll leave midway.”

It will be understandably difficult to watch. The opera, “An American Soldier,” by the composer Huang Ruo and the playwright David Henry Hwang, which is having its premiere in a newly expanded version at the Opera Theater of St. Louis on Sunday, tells the story of her son, Danny Chen, a native New Yorker who enlisted in the Army and was deployed to Afghanistan.

Soon after he got there, in 2011, he was subjected to brutal hazing and racist taunts by fellow soldiers in his battalion, and killed himself. He was 19.