Since early 2007 a new breed of combatants has appeared on the streets of Mogadishu and other towns in Somalia: the 'Shabaab', or youth, the only self-proclaimed branch of al-Qaeda to have gained acceptance (and praise) from Ayman al-Zawahiri and 'AQ centre' in Afghanistan. Itself an offshoot of the Islamic Courts Union, which split in 2006, Shabaab has imposed Sharia law and is also heavily influenced by local clan structures within Somalia itself. It remains an infamous and widely discussed, yet little-researched and understood, Islamist group. Hansen's remarkable book attempts to go beyond...