In the past five years more than four million Iraqis - 20 per cent of the entire population - have been driven from their homes as a result of the war and sectarian bloodshed. Two million have become exiles, living desperate lives across the border in Syria and Jordan. Filmmaker Sharmeen Obaid-Chinoy, a Stanford alumna, investigates the biggest and most catastrophic refugee crisis in the Middle East since the Palestinian diaspora of 1948.