In the previous adventure, The Seven Crystal Balls, seven explorers have been afflicted with a mysterious illness after unearthing the tomb of the mummified Inca, Rascar Capac. Professor Calculus has been kidnapped by a band of men including the Indian Chiquito, one of the last descendants of the Incas. Tintin and Captain Haddock discover their friend is on board the cargo ship Pachacamac bound for Callao, Peru and are on a flight to rescue him.
