Tintin, Snowy and Captain Haddock have a kidnapping on their hands. Professor Calculus has vanished. His disappearance is certainly connected with an ancient curse of the Incas, and the trail leads to Peru. But everyone fears the vengeance of the Prince of the Sun and only Zorrino, the young orange-seller will help them. High into the Andes they go, but the perilous journey ends in a dungeon and the prisoners face a hideous end. In this sequel to ''The Seven Crystal Balls'' Tintin is involved in one of his strangest and most colourful adventures.