In 1995, Kamel Daoudi, a twenty-one-year-old engineering student from the suburbs of Paris, moved out of his parents’ apartment. He had fought with his father, an Algerian immigrant obsessed with the possibility of his son’s success in France, his “acceptance by the system,” in Daoudi’s words. He resented his father and, determined to find a different path, took up the ideals of jihad.
At a small prayer hall in his parents’ neighborhood, he met a group of like-minded men, older Algerians who felt adrift in their adopted country. France seemed to them a place of libertine excess, Daoudi said,…