In this book, Fouad Ajami analyzes the struggle for influence along the Fertile Crescent--the stretch of land that runs from Iran's border with Iraq to the Mediterranean--among three of the regional powers who have stepped into the vacuum left by the West: Iran, Turkey, and Saudi Arabia. He explains that, of the three powers competing for influence, Saudi Arabia and Iran are in it for the long haul. Each of those powers has a sense of mission and...