Underwater archaeologist Jack Howard is back with a dangerous mission to uncover a shocking secret which could rewrite history. In 1890, a British soldier emerges from the depths of a Cairo sewer. He claims to have been trapped for years in an ancient underground complex, and swears that he stumbled upon an incredible collection of gold, treasure and thousands upon thousands of jars filled with papyri. Dismissed as a madman who has lost his mind in the desert, his story was lost to the world - until now