Stephen Sackur speaks to Jürgen Todenhöfer. The so-called Islamic State movement has very publicly murdered western journalists and aid workers who entered its territory. As a result, IS-held areas of Syria and Iraq have been off-limits to western reporters for the past year. Except for the guest today. Last December Jürgen Todenhöfer spent ten days inside the self-styled IS caliphate. He emerged unscathed with a remarkable story - what more can he tell us about the jihadists, and what can we conclude about his own motivations?