Horace Holly & his ward Leo Vincey once again embark on a quest to find the mysterious woman known as Ayesha. Knowing that She is no longer in Africa, they go east, eventually reaching a lamasery in the mountains of Tibet. The abbot warns them against continuing, but they press on & discover an ancient city named Kaloon, which is ruled by the evil Khan Rassen & his imperious wife, the Khania Atene. Near the city is a huge volcano, wherein lives the Hesea, the Priestess of Hes, & her servants. Leo becomes the center of a conflict between Atene & the Hesea, both of whom desire him.