Gibo and Bomba are returning to the molocca of Horuhun, after their adventures on the Underground River during which Sobrinini died in glorious fashion. The pair carry the contents of Sobrinini's chest they had uncovered along the river's bank, which will reveal most of the secrets of Bomba's past to the recovering Cody Casson. But this becomes a moot point as you shall see.
Escaping the dangers of a gale (complete with flood), savage animal attacks (of the usual assortment: jaguar, puma, anaconda , alligator, boa and cooanardi) and the inevitable head-hunters, Bomba and Gibo finally make it back to the molocca along with three explorers they had rescued en route.
One of the three lost explorers is Andrew Barton, the discoverer of Bomba, but he is unconscious for the most part and doesn't realize that his fourteen year hunt for his kidnapped son is over. But Bomba knows, yet must await his discoverer's recovery before their reunion can be complete. But then Nascanora and his head-hunters attack in there fiercest assault ever. They come close to overwhelming the Anaru but Bomba turns the tide and the invaders from the Giant Cataract are decimated, almost to extinction, their power broken for generations. Even the head-hunters leadership is destroyed, with the deaths of Co-Chieftains Nascanora and Tocarora and the Medicine Men Ruspak and Ganyuk.
To top it all off, Bomba's other discoverer, Laura, is contacted by Andrew's two fellow explorers, and arrives at the molocca of Horuhun Hondara on the penultimate page. Yea, that scene prompted a tear or two...
By book's end, the family, with Cody and Gibo, prepare to leave for Rio de Janeiro and then home in America. All is well and seemingly, the series is over but Bomba's last utterances are a hint of the adventures in Africa and Asia to come: "But some day the jungle will see me again. It is life to me. I cannot live without it."
Next up, New York City and Africa as Bomba journeys to a "strange land," but does the author mean America or Africa in the title? Stay fucking tuned!