Pharaoh by David Gibbins
1334 BC: Akhenaten the Sun-Pharoah rules supreme in Egypt. The young Tutahkhamun is groomed to be his successor. But then Akhenaten disappears and his legacy is seemingly swallowed up by the sands that lie under modern Cairo and the great pyramids of Giza ...
AD 1885: A half-crazed man appears claiming to know of a vast lost labyrinth beneath modern Cairo, of canals and palaces and tombs. His story won't be believed for almost thirty years, with the discovery of Tutahkhamun's tomb in 1924.
Present-day: Jack Howard and his team are excavating one of the most amazing underwater sites they have ever encountered. They hear the story of the crazed engineer. What follows is a rollercoaster ride of adventure and action, as they dive into the Nile into a world three thousand years back in history, inhabited by a people who have sworn to guard the greatest secret of all time...