Dust of Death, a Doc Savage Adventure

The tiny South American republics of Santa Amoza and Delezon were at war with a mysterious hooded figure known as the Inca in Gray. He appeared and began slaughtering citizens of both sides with a strange dust that brought instant writhing death. Doc Savage and his crew rush to the Amazonian forest in hopes of saving lives, but all they find when they get there is a firing squad ready to execute Doc Savage himself.