In Undercover Muslim, Theo Padnos brilliantly evokes a landscape and journey that few Westerners have experienced. He investigates the radicalisation of disaffected young men as they move, almost unnoticed, from London, Berlin or Paris to their new spiritual home in Yemen. Padnos' journey takes him from the newsroom of a Yemeni newspaper to the prayer rows and lecture rooms of Yemen's madrassas, from covert Jeep rides into the sacred mountains to a stint in an overcrowded prison. It is through these events, and through the people he encounters, that Padnos shows us how a terrifying gulf has...