Aimen Dean was a trusted member of Al Qaeda's inner sanctum in Afghanistan in the late 1990s. With his Quranic learning and fervent commitment to holy war, this young Saudi received a personal audience with Osama Bin Laden and came to know most of Al Qaeda's key leaders. But Aiman Dean did not share the group's enthusiasm for terror attacks inflicting mass civilian casualties. After the bombings of US embassies in Africa in 1998, he left Afghanistan and began working as an informant for the UK security services. What does his extraordinary story tell us about the nature of the jihadist threat?