A fabulous cache of gold and jewels is hidden in the temple of Opar, where a savage cult sacrifices young virgins to their angry fire god. Tarzan is on a quest to seize the treasure, but his many enemies conspire on all sides to interfere. Crazed La, the sultry high-priestess of Opar, is determined to win the Lord of the Jungle as her lover, and slave trader Achmet Zek does his part to help her by kidnapping Tarzan's mate, Lady Jane. Meanwhile, a double-crossing friend of Tarzan's, Albert Werper, is out to steal the jewels of Opar for himself. The dangers increase when a severe blow to the head gives the Ape Man amnesia, imperiling both his mission and his beloved Jane.

The star of Tarzan the Tiger, Frank Merrill, was a former champion gymnast with a muscular build befitting the role of the mighty King of the Jungle and worked as a stunt double for the original Tarzan, Elmo Lincoln. Awarded the starring role after daredevil Joe Bonomo broke his leg, Merrill introduced rope climbing and vine swinging acrobatics to Tarzan's repertoire. This 15 part adventure serial was Merrill's eighteenth and final screen appearance. Apparently unable to make the transition to talkies, he retired from motion pictures to become Park Commissioner for the city of Los Angeles.