In January, The New Yorker’s Ben Taub travelled to Mauritania to meet with Mohamedou Salahi. An electrical engineer who had lived in Germany, Salahi was detained at Guantánamo Bay for fifteen years and tortured, despite the fact that he was not a terrorist. But one of the key pieces of evidence was that Salahi’s cousin, known as Abu Hafs al-Mauritani, was a high-ranking member of Al Qaeda—a member of the group’s governing Shura Council and a spiritual adviser to Osama bin Laden, who had drafted bin Laden’s infamous fatwa against the United States. While Salahi endured torture at Guantánamo, Abu Hafs was never captured or detained by the United States. When Ben Taub met Abu Hafs at a wedding of Mauritanian élites, he wondered how this man had gone free while his cousin had suffered so much. Abu Hafs agreed to an interview, but it quickly took a turn that Ben didn’t expect.