 The cult of Ubasti, headquartered on the isle of Lemuria, believes that Princess Nadji of Egypt is a reincarnation of their long-dead goddess, Ossana, and intend to sacrifice her so that Ossana may be resurrected. Nadji has sought refuge at the California home of Frank Chandler, an American educated in the Ancient East and familiar with White Magic and thus calls himself "Chandu". Vindhyan, high priest of the cult s California base has learned of this, however, and works his Black Magic to gain control of Nadji. Chandu is able to rescue her but she is in a deep trance which he cannot penetrate, so attempts to move her to safety in the South Seas, unaware that the cult has a base there also and that Vindhyan has stowed aboard his chartered yacht...