In this 1947 and '48 sequel to The Seven Crystal Balls Tintin, Snowy and Captain Haddock travel high into the Peruvian Andes in search of the kidnapped Professor Calculus. Helped by Zorrino, the young orange-seller, the perilous journey ends in a dungeon where the prisoners face a hideous end. Herge's research for this story was considerable...from South American scenes to the interior of the Inca tombs, actual archaeological examples fom Tiahuanaco and Sacsahuaman as well as extensive travelers' accounts and pictures were used to create an incredibly rich story.