After a guide for an archaeological expedition is killed, Tarzan decides to accompany the group in their quest to enter the forbidden "City Of Death", not only to protect them, but also to find out why a plant specialist and an ambitious colonel are also so interested in the place.

After uncovering the mythical Blue Stone of Baskar, Colonel Tatakombi takes advantage of the legend associated with it to declare himself the leader/god of the surrounding tribes, in the hope of later taking control of the country. Tarzan is determined to expose and stop him.