Edgar Rice Burroughs 
Tarzan and the Jewels of Opar 

A novel by American author Edgar Rice Burroughs, Tarzan and the Jewels of Opar is the fifth of a 24-book series he wrote on the titular Tarzan. It was first published in the November and December 1916 issues of All-Story Cavalier Weekly, and Mc Clurg published the first volume in 1918. In order to make up for some recent financial setbacks, Tarzan travels back to Opar, the location of a forgotten Atlantean colony and the source of its wealth. There is a significant cache of gold that was mined while Atlantis itself was submerged beneath the waves thousands of years ago, but which is now lost to the memory of the Oparians and only Tarzan is aware of its hidden position. Tarzan is discreetly followed to Opar by Albert Werper, a rapacious, outlawed Belgian army commander working for a crooked Arab. After getting hit on the head by a boulder that was falling during an earthquake in the treasure room, Tarzan there loses his memory. She had fallen in love with the apeman during their first encounter, and La and her high priests are not going to let Tarzan escape their sacrificial knives this time.