Bone Robbers on the Orinoco

11-year-old Pedro and former slave boy Abasi are travelling along the Orinoco River in the company of the explorer Alexander von Humboldt and his companion Aimé Bonpland. Their destination is the bone cave of Ataruipe, a sacred tribal burial ground that is beset by mysterious and eerie stories. Humboldt goes too far when he steals one of the holy skeletons, and the tribe's revenge is swift - Humbolt and Bonpland are kidnapped. Now Pedro and Abasi are left on their own, but they have a clever ploy that might just save the two explorers.