Adventurer Simon Reeve travels from source to sea along the world's longest river, the Nile. His journey will take him from the holy source of the Blue Nile in the Ethiopian highlands, through the desert of Sudan and onwards through Egypt to the Mediterranean Sea. The life-giving river has forged some of our earliest civilisations and influenced some of our greatest religions. But with populations along its banks rising fast, Nile countries are demanding an ever-greater share of the sacred waters, threatening the stability of the entire region.