For the best part of 400 years, explorers have searched the deep canyons & towering ice peaks of these mist-covered cloud forests trying to locate the lost cities of the Inca. They were all after one thing; gold. Any gold would do but there was one thing desired above all others, the Great Golden Disc of the Sun. The most sacred of all Inca relics. The Inca Holy Grail. It is in search of this Holy Grail that David Adams goes on his journey to Puncuyoc, sacred Sister City of Machu Picchu; the city sought but never found by Hiram Bingham.