This serial-esque action epic is told in two parts. In the first part, "The Golden Lake", man-of-action Kay Hoog (Carl de Vogt) heads for South America to look for a secret city of Incas living in temples much as they did centuries ago. They have a Harvard professor prisoner, and are also sitting atop a huge gold mine. Kay is challenged in his quest by the Spiders, a secret multi-national criminal organization. Their chief agent Lio Sha (Ressel Orla) has the hots for Hoog, but she won't let that get in her way of taking the gold for her gang. Kay makes cute with Inca priestess Naela (Lil Dagover), which really peeves Lio Sha. In the second part, "The Diamond Ship", Kay Hoog is once again racing against the Spiders, this time in search of the Buddha diamond, a fabulous gem that is foretold to be the great emancipator of Asia from the control of the West.
There's a lot going here, with secret societies, hidden cities, cowboys, pirates, guys dressed like ninjas, a samurai, safecrackers in top hats and domino masks, human sacrifice, clairvoyants, hot air balloon rides, and much more. Despite the 137 minute running time, I was rarely bored, although the first half is much better than the second. It also ends rather abruptly, as this was originally intended to be quickly followed up by another 2-hour, 2-part installment in the war between Hoog and the Spiders, but that never got made. Instead, Lang was inspired to bring Mabuse to the screen, and the rest is history.
Forgive me for reviewing both episodes together, but things just fit together better in this format.