Willy takes Dr. Reynolds to Kangaland to meet his people, but when they get there they discover that a witch doctor has seized control during the chief's sickness. Reynolds gives the chief a shot of penicillin to cure his illness, but before it can take effect, the witch doctor captures Reynolds and prepares to burn him at the stake.
Conway, a somewhat crazed ventriloquist, wanders into Ramar's camp after having been lost in the jungle. The natives, seeing Conway's dummy, believe it to be a god, steal it, and bring it to their village to worship on a shrine. When Conway risks his life to get the dummy back, Ramar begins to suspect that there's more to it than Conway's affection for his dummy, and thinks that the dummy may be filled with stolen radium.
Chief Matumbo sends for Dr. Reynolds to try to help an explorer who is dying from a mysterious illness. When the doctor arrives at the village, however, the natives try to kill him. It turns out that the dying man is holding a secret that someone is trying to make him tell using voodoo, and Reynolds must find out what that secret is in order to discover who is using the voodoo on him.
A safari ends disastrously when all the native guides and their leader are mysteriously murdered. The only survivor is the leader's wife, and the superstitious natives believe she is a witch who caused the disaster, and demand her death. Dr. Reynolds protects her while trying to find out what really happened on the safari.
Dr. Reynold and Prof. Ogden are suddenly attacked by a tribe whose members are wearing a distinctive blue face paint, something neither of the men has ever seen before. The attackers are driven off, but Reynolds and Ogden manage to wound and capture one of the warriors. While the native recovers from his injuries, Tom, Howard and Charlie set out to discover what caused the unprovoked attack, and find out the meaning of the mysterious blue face paint.
Prof. Ogden is attacked by a member of the sinister Shaitan devil-worshiping cult, and when he awakes he has the mark of Shaitan burned into his hand. The legend is that when the mark disappears the person will die, and as the symbol begins to fade away, Ogden gets sicker and sicker. Dr. Reynolds must race against time to unlock the secrets of the Shaitan cult before Ogden dies.
Ramar and Prof. Ogden come across two botanists who have just, they claim, killed their native guide in self-defense. Believing their story, the men are offered lodging for the night at Ramar's camp. However, what Ramar and Ogden don't know is that the men aren't really botanists but narcotics traffickers in Africa looking for new supplies, and they are taking a great interest in Ramar's and Ogden's new--and unpatented--medicines.
An American trader can't convince the chief of a native tribe to exchange their ivory for gold. However, the village's corrupt witch doctor is more than happy to make the trade and, unknown to the chief, strikes a deal with the trader to steal the tribe's ivory in exchange for the gold. To cover his tracks, though, the witch doctor frames another tribesman for the crime--the chief's son, who happens to be a friend of Ramar's.
Ramar hears about a rare substance that halts the effects of aging. The only problem is that it is in territory controlled by The White Goddess, where white men are forbidden to enter. Nevertheless, Ramar is determined to make contact with her, but discovers that he's not the only one--two dangerous escaped convicts are looking for her, too.