HE WINCED AT the mere mention of his son's name, visibly overcome by an unceasing thought that he struggled to articulate. He looked down to hide the tears in his eyes. "You have to understand, I am in pain," said Yaken Aly, choking on the words: "My son is gone." Aly raised his son, Islam Yaken, in Heliopolis, a middle-class Cairo neighborhood with gardens and trendy coffee shops, and sent him to a private school, where he studied in French.