Chandu on the Magic Isle

With the help of black magic, Vitras, the High Priest of Ubasti, the Cat Worshippers, tricks Egyptian Princess Nadji into believing that her lover, Frank Chandler (also known as Chandu, the Magician), is using his psychic powers to draw her to a certain place. When Nadji, who is wanted by the Ubasti for a sacrificial ceremony in which her life force will be used to revive Princess Ossana, their deceased monarch, arrives at the spot where Vitras' telepathic communications have led her, she is transported through a magic circle of fire to the island of Lemuria. Frank, his sister, Dorothy Regent, and his nephew Bob and niece Betty pursue Vitras in Frank's yacht, but the Ubasti place a curse on the boat and incite Frank's crew to destroy the vessel. While Frank and the Regents struggle to swim safely to Lemuria's shore, Nadji is told by The Voice of Ubasti that she has only seven days to live. Once on the island, Frank leaves the Regents on the beach and follows the tracks of the Cat Worshippers to the Pyramid of Fear where Nadji is being held captive. As he nears the Pyramid's entrance, Frank falls into a hidden pit and wanders through a underground maze. At the same time, the Regents are captured by Vitras' men. Stripped of his supernatural powers by Vitras, Frank uses his magic ring to seek advise from Yogi, his spiritual teacher, and finally locates Nadji's cell. Vitras, however, interrupts Frank's attempt to talk to Nadji and, using the circle of fire, transports her into the fourth dimension, where she is rendered invisible. Temporarily thwarted, Frank returns to the maze and stumbles on the cell on Tyba, a powerful white magician and Frank's former teacher, who has been incarcerated by the Ubasti. Frank's liberation of Tyba invokes the fury of The Voice of Ubasti, who prepares to burn the Regents at the stake. After the two magicians cross a tiger-filled pit, Frank consults the Yogi through his ring and is instructed to use the High Incantation, a powerful curse that destroys the user's magical abilities. To avoid using the Incantation, Tyba invokes his own circle of fire and makes Frank invisible. While Frank rescues Nadji, Tyba frees Bob. Frank's invisibility, however, soon wears off, and both Nadji and he are recaptured by Vitras. Through Tyba's crystal ball, Tyba and Bob see Frank tied up under a suspended slab of rock that is being lowered slowly onto his body by one of Vitras' henchmen. After a fierce fight, Bob and Tyba save Frank from the slab and rush to the temple where Nadji is about to be sacrificed. At the ceremony, The Voice of Ubasti demands that Nadji renounce Frank, and the princess agrees on condition that Frank and the Regents not be harmed. In spite of his promise, The Voice of Ubasti orders the Regents to be burned alive. Before Nadji is thrown into the sacrificial pit, Frank renounces his love of Nadji so that he can invoke the High Incantation and strip Vitras of his power. The Incantation causes the temple to collapse and the island volcano to erupt. In the ensuing chaos, Frank rescues Nadji, and Tyba saves the Regents. Back in San Francisco, Frank uses his restored magical powers to make Nadji and himself disappear before a group of anxious, prying reporters.