The tribal leaders from unexplored jungles gather to meet with the Phantom, a supreme ruler who has taught the people to live together in harmony.

Professor Davidson searches for the missing part of a map that shows how to reach the lost city of Zoloz; the Phantom is trapped by another faction, headed by Dr Bremmer, the secret agent head of a ring of foreign saboteurs.

The Phantom discovers that a number of outlaws plan to attack the Davidson expedition, and chases the desperados into the jungle.

Fearing that Professor Davidson and his associates will learn of his plans, Dr Bremmer has his men capture the expedition.

In an effort to solve the theft of the ivory keys, the Phantom disguises himself, but also learns of a gun-running plot.

On their way to Sitanna, Byron and Mokue are ambushed and The Phantom comes to their rescue before speeding off to stop the villains at Omdor Gorge.