This story offers a rare opportunity to feel as though you're actually taking part in an awesome expedition to an Amazonian plateau where there are still some surviving prehistoric animals. It's a rarity labeled science fiction, and it is at least relatively scientific. As for the fiction part, who knows?
A young reporter, Edward "Eddie" Malone wants to impress a female inamorata looking for a great man capable of brave deeds and actions, so he asks for a dangerous assignment that leads to the South American derring-dos he hopes will attract her attention.
Conan Doyle had written a half dozen stories about Sherlock Holmes, beginning in 1887 before this book was published in 1912. He wanted a change and once wrote his mother, "I think of slaying Holmes and winding him up for good and all. He takes my mind from other things." In this particular story, details are given by an impersonal historical narrator, with Doyle using him to provide at least a sense of credibility.
We won't tell you the results of the reporter's love affair. You'll just have to listen to find out.
