An author/explorer travels to Peru to find the missing uncle of his young companion. Her archaeologist uncle vanished while searching for a lost Incan city he located on an ancient map. The writer and the girl join forces on an expedition to locate the legendary city, guided by a fellow American archaeologist who stole the map from her uncle. He intends to find the city with his gang of thieves and loot it. Their journey is fraught with peril: snakes, crocodiles, jaguars, and quicksand. The writer and the niece encounter the Incas and warn them of the danger. The indigenous people swiftly defeat the archaeologist and his thieves.