A secret kingdom is located in the mountainside, where the Pima Indians serve the Sun God's chosen people. Kit Willer and the pima chief's daughter Nahua have been chosen as victims of the party expenses, but Tex has also found his way into the mountain's yumen. When the true side of things dawns on Tex, he hatches a cunning plot to free a tribe long enslaved. But the High Priest of the Sons of the Sun has surprising abilities, and he is not about to give up his throne in peace.