Directorate S is a covert department within Pakistan’s Inter-Services Intelligence (ISI) agency. It is dedicated to supporting Islamist radicals, Kashmiri separatists and the Afghan Taliban. ISI has always been led by a three-star army general, answerable to the chief of the general staff. For much of the period covered by Steve Coll’s book, General Ashfaq Kayani loomed large, serving as director-general of ISI from 2004 to 2007, before becoming chief of army staff. He figures prominently in Coll’s account, often veiled by a cloud of cigarette smoke.