Mr. Wisnia talked about his children, his time in the American Army. Ms. Tichauer spoke about her humanitarian work after the war and her husband. She marveled at Mr. Wisnia’s perfect English. “My God,” she said. “I never thought that we would see each other again — and in New York.”

The reunion lasted about two hours. He finally had to ask: Did she have something to do with the fact that he’d managed to survive in Auschwitz all that time?

She held up her hand to display five fingers. Her voice was loud, her Slovakian accent deep. “I saved you five times from bad shipment,” she said.

“I knew she would do that,” said Mr. Wisnia to his grandchildren. “It’s absolutely amazing. Amazing.”