Format: Global Grey free PDF, epub, Kindle ebook
Pages (PDF): 211
Publication Date: 1928
This is the eleventh book in the Tarzan Series, given that the previous two (The Tarzan Twins and Tarzan and the Tarzan Twins, with Jad-bal-ja, the Golden Lion) are not considered to be a part of the main series due to the fact that they are children's books. In this adventure, Tarzan finds an outpost of European knights and crusaders from a "forbidden valley" hidden in the mountains. His lion ally Jad-bal-ja puts in an appearance late in the book.