Tantor drinks water from the river and gets ill. Tarzan, Jane, and the Professor go upstream to find out what's poisoning the river while Terk tries to save Tantor. Along the way, they lose their boat and get captured by a group of natives who blame them for poisoning the river.

While the gang is setting up a surprise croquet game for the Professor, Jane encounters an ill-looking fawn. Upon touching the fawn, the soul of Queen La enters her body. Failing to return to Opar by herself, La turns to Tarzan, who senses something wrong right away. Instead, she turns to Dumont for help. Can the aid of Usula, the Waziri elder, bring Jane back before La retrieves her staff and brings Opar to life again?