Through his work at the Brookings Doha Center, Lister has participated in so-called Track II diplomacy—unofficial contacts between influential nonstate actors—with leaders and rank-and-file members of jihadist factions in Iraq and Syria. Those experiences inform this book, which is the most thorough chronicle yet of jihadist activity in the region since 2011. According to Lister, the 2013 split between al Qaeda’s Syrian affiliate (Jabhat al-Nusra) and the Islamic State (also known as ISIS) was provoked by strategic differences, not doctrinal ones. Al Qaeda wants to embed itself in local disputes and create operational safe havens, whereas ISIS wants to hold territory and govern. Intelligence services in Syria, Turkey, the United States, and elsewhere have played footsie with various jihadist groups. The Assad regime in Syria dispatched jihadists to Iraq in 2006 only to watch them return home, to deadly effect, in 2011. Lister details these developments but reveals less about crucial issues such as how various jihadist groups recruit new members, what motivates recruits, how they are paid, and how many casualties jihadist infighting has produced. He also does not address scenarios in which foreign patrons might abandon their proxies in Syria or the question of whether Iran must be defanged before the Sunni world will grow out of its jihadist obsessions.