In ISIS: Inside the Army of Terror, American journalist Michael Weiss and Syrian analyst Hassan Hassan explain how these violent extremists evolved from a nearly defeated Iraqi insurgent group into a jihadi army of international volunteers who behead Western hostages in slickly produced videos and have conquered territory equal to the size of Great Britain. Weiss and Hassan explain the key players and their origins, and how the movement has gained support. This new edition is fully revised and updated, covering events that took place in 2015.