Tintin and Captain Haddock arrive in Peru to look for Professor Calculus, following the events in The Seven Crystal Balls, which ended with Calculus being kidnapped for putting on the bracelet of the mummified Inca, Rascar Capac. Although Tintin and Haddock intercept the ship carrying Calculus, the Pachacamac, near Callao, they are unable to rescue him, and they set off on the trail of the Quechua-speaking natives who have taken him. It leads them to the mountain town of Jauga, where a train is sabotaged in an attempt to kill them. They find both the authorities and the locals extremely unwilling to help them track Calculus' kidnappers because of the wrath of the Inca. Read on to find out what happens next...