Books like Tarzan the Invincible

When I was 10 years old, my father gave me three books for Christmas: Treasure Island, The Swiss Family Robinson, and Tarzan and the Golden Lion. At the time, these were all a little advanced for me but when I reached my teen years, I finally read the Tarzan book and was hooked on his adventures. My older brother also had a copy of Tarzan and the Ant Men which I still consider one of the best in the series. In the 80s, I decided to read all of the Tarzan adventures in order but only made it as far as Tarzan at the Earth's Core and then for some reason I stopped reading them. In the mean time, I started collecting Burroughs editions in hard cover and now have a near-complete set of his books. So I kept seeing the books on their shelves and decided to read the next Tarzan adventure, Tarzan the Invincible.This book was originally published in Blue Book magazine from October 1930 through April 1931 as Tarzan, Guard of the Jungle.The plot of this one has Tarzan coming upon a group of Soviet communists who are hatching a very convoluted plot to attack Italian Somalia in the guise of French troops thereby starting a war between Italy and France which they hope will embroil Europe in another world war leaving the Communists to pick up the pieces. The leader of the group is hoping to become emperor of all of Africa. Part of the scheme is to get gold to finance this coup from the treasure vaults of the lost city of Opar. Well Tarzan overhears this and immediately goes to Opar to find that La, the high priestess of the city, has been overthrown and placed in a cell. Tarzan rescues her but she winds up wandering lost in the jungle. Others are also lost in the jungle including some of the communists including a beautiful woman named Zora. A lot of the story has Tarzan looking for La and others looking for Zora. Tarzan gets help from his faithful Waziri to stop the communists and eventually reinstate La to her rightful place in Opar.Well, its been decades since I last read a Tarzan novel and this one definitely did not grab me like the earlier books in the series. Too much wandering in the jungle with not enough plot. This is the fouth book to feature Opar and I believe the last. I know Opar was also a story line in the first Tarzan book I read, Golden Lion. I'll probably read more of these, along with other Burroughs novels, at some point but I'm really not in a rush to do so.