Stone McGuire and the Lost Inca Gold is based on history. The story depicts Francisco Pizarro and the ransom of the Inca king, Atahualpa. The legend of the Inca gold hidden in the mountains of Ecuador was revived in the 1850s when a copy of Valverde's Guide was found in the archives in the city of Latacunga, Ecuador. The Inca quipus, the knotted cord devices used by the Incas to keep records, are accurately portrayed. The 'fraternity' of world leaders that meet once a year, called a think-tank b