Why would anyone in their right mind go wandering into the jungle? Sure it's pretty from the outside and there's a lot of interesting plants and animals, but those animals make some really scary noises once you get more than a few steps into it (as Teddy Roosevelt found out). I guess there's also long been rumors of gold and untold wealth just waiting to be found, and that might be enticement enough for some brave explorer. Or maybe he just had a really wimpy name and wanted to prove he was a man.
As long as Europeans have been visiting and colonizing the Americas there have been legends of an ancient city of gold in the jungle. Thousands have lost their lives searching for El Dorado, and in 1925 the famed British explorer Percy Fawcett, funded by the Royal Geographical Society, set off with a small group consisting only of his son, Jack, and one of Jack's friends. This was still the romantic era of exploration, when the last corners of the map were being filled in, and the expedition had excited the imagination of many. Perhaps unsurprisingly, Fawcett's expedition was never heard from again.
It's not deep or scholarly history, but reads like an exciting adventure tale. I listened to the audio book and, having lived in Brazil myself for a couple of years, was a little bothered by some of the pronunciations. The narrator repeatedly mispronounces Manaus (saying manNOOSE, instead of muhNOWSE), and there were a few Portuguese translations that I found questionable, although it has been quite a few years and I could be wrong. Nevertheless, it's an exciting read. And who knows, maybe good ol' Percy found Z after all.