A weeping Kim-Hoan Thi Nguyen kissed her 7-year-old son goodbye at the Ho Chi Minh airport and told him it would be a long time before they would be together again. Little Binh Le boarded the plane and flew off to the States, where his mother hoped he would flourish. It was 1991. She next saw Le when he visited Vietnam at 12. He cooked her french fries. He visited again when he was 18 and a recent graduate of Edison High School in Fairfax County. They had a party. Their next reunion came in December 2004. At his funeral,...