Craig Unger begins his House of Bush House of Saud, a massive seller in the US likened to All the President's Men, with an explosive question: how is it that two days after the attack on the World Trade Centre, when U.S. air traffic was tightly restricted, 140 Saudis, many immediate kin to Osama Bin Laden, were permitted to leave the country without being questioned by U.S. intelligence? The answer lies in a hidden relationship that began in the 1970s, when the oil-rich House of Saud began courting American politicians in a bid for military protection, influence, and investment opportunity. With the Bush family, the Saudis hit a gusher - direct access to presidents Reagan, George H.W. Bush, and George W. Bush. To trace the amazing weave of Saud-Bush connections, Unger interviewed three former directors of the CIA, top Saudi and Israeli intelligence officials, and more than one hundred other sources. His access to major players is unparalleled and often exclusive - including executives at the Carlyle Group, the giant investment firm where the House of Bush and the House of Saud each has a major stake.