Doc and Dick are cousins, but they are often called "The Tarzan Twins" because of they look very much alike. They are distant relatives of Tarzan's, and have been invited to spend their holidays with him. When they get lost in the jungle, they experience all kinds of adventurous situations: they are captured by a hostile tribe, seek shelter from a terrible storm and end up saving a missionary's daughter from the savages of Opar.; Queen Zulena returns to the city of Tungelu together with her husband Natongo, only to find it destroyed. When they find a hidden passage, it leads them to a group of remaining Tungelu warriors undet the command of N'Glomi. He tells them that the women and the children have been abducted by the Tuaregs.