Bomba the Jungle Boy is about thirteen years old and has no memories of his parents. He has been nurtured by Gibo and Wafi's parents, who are neighbours of Cody Carson in a remote region of the Amazon Forest. Bomba yearns to discover who his parents are or were but Cody's mind is clouded with only an occasional moment of lucidity here and there. One day, while roaming the Amazon jungle, Bomba meets the explorers Dorn and Gillis and in doing so, saves their entire camp from a savage jaguar attack. Promising to return one day, they leave gifts (including a pistol) and then head for the coast while Bomba soon runs into a party of dreaded headhunters from the distant Giant Cataract. After escaping their clutches initially, the jungle boy secures the friendship of a local tribe, the Anaru, the friends and family of his mother's maternal grandfather, before racing back to Cody, to defend all he holds dear.
Combating snakes, a caiman, vultures, pumas and vampire bats, Bomba returns to the hut he shares with the old naturalist, Cody Carson and by trickery, courage and the stout friendship of his local animal friends, they defeat the marauders.
Cody, who experiences moments of lucidity, recalls the names Vassaro Rossi and Arnka and adds that Jojasta, the Medicine Man of the distant Moving Mountain, can shed some light on Bomba's parentage. It is to this terrible land that Bomba will go to next, in his quest for knowledge of his past and origins!