The so-calle Islamic State, or ISIS, has inspired young men and women all over the world to commit horrible atrocities in its name. They have flooded into the Islamic State's stronghold in Syria and Iraq and carried out attacks under its black banner in nearly every continent, most recently in Paris. How has the Islamic State surpassed al-Qaeda to become the most popular jihadist group on the planet? Its chilling mission is very specific: bring the immediate return of the Islamic empire and look ahead to the imminent doomsday. These two founding ideas, combined with a highly intelligent, meticulously organized membership, account for its popularity and shape its behavior. Its goal is not only to revive the Islamic empire but also usher in the End of Times--a concept that means ISIS anticipates a final battle that will restore the Muslim community to its medieval glory days. And they will not stop until they achieve their mission.Based almost entirely on primary sources in Arabic--including exclusive al-Qaeda memos that have not been made public before--The ISIS Apocalypse explores how these two powerful ideas shaped the Islamic State's past and foreshadow its dark future, and seeks to explain the popularity of the Islamic State and its violent, terrifying behavior.